How can aspirin help you? What the research says

Aspirin is a widely available over-the-counter medication that shows substantial effects at promoting survival and reducing risk of many types of cancer, plus reducing inflammation and managing pain due to inflammation.

How can aspirin help you? What the research says

We summarize the clinical evidence for each medical benefit here. We begin with our assessment of the strength of evidence within each category, followed by a brief summary of individual studies or reviews of several studies. In assessing the strength of evidence, we consider the study design, number of participants, and the size of the treatment effect (how much outcomes changed with treatment).

To see more details, click the plus sign to the right of any section.

Our assessments of evidence for each medical benefit fall into one of these categories:

Strong evidence: consistent, significant effects in several large (or at least one very large) well designed clinical studies or at least two meta-analysesa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of clinical studies of moderate or better quality (or one large meta-analysis) finding similar results
Good evidence: significant effects in one large or several mid-sized and well-designed clinical studies ( randomized controlled trialsa study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects with an appropriate placebo or other strong comparison control or observational studies that control for confounds)
Modest evidence: significant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies), or several small studies aggregated into a meta-analysis
Preliminary evidence: significant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect
Weak evidence: one or more case studies, supported by animal evidence OR small treatment effects of limited clinical significance OR studies with no controls OR weak trends of effects
Insufficient evidence: preclinical evidence only OR clinical studies with such poor or unclear methodology that no conclusion can be drawn OR conflicting findings across clinical studies with no preponderance of evidence in one direction; conflicting evidence occurs when studies find conflicting effects (positive effect vs no effect or negative effect) with the same treatment and the same general study population (same cancer type, for example)

Learn more about how we research and rate therapies and practices in How We Rate Therapies ›

Selected preclinical evidence is in Are you a health professional? ›

Improving treatment outcomes

Is aspirin linked to improved survival? Is it linked to less cancer growth or metastasis? Does it enhance the anticancer action of other treatments or therapies? We present the evidence.

Cancer as a whole

Strong evidenceconsistent, significant effects in several large (or at least one very large) well designed clinical studies or at least two meta-analyses of clinical studies of moderate or better quality (or one large meta-analysis) finding similar results (this is the CancerChoices definition; other researchers and studies may define this differently) of lower mortality among people with adenocarcinoma using aspirin regularly, particularly among those without metastasis

Strong evidence of substantially fewer metastases with cancer as a whole among people using aspirin

Mortality: strong evidence of lower mortality among people with adenocarcinoma using aspirin regularly, particularly among those without metastasis, and with greater benefit among people who smoke

Good evidence of better progression-free survival but no evidence of an effect on overall survival among people with cancer as a whole treated with low-dose aspirin during treatment with immune checkpoint inhibitors

50% lower mortality among people with adenocarcinoma, particularly in those without metastasis at diagnosis, with regular aspirin use before and after diagnosis compared to controls, with greater benefit among people who smoke, in a pooled analysis of 5 very large RCTsrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects¹Rothwell PM, Wilson M et al. Effect of daily aspirin on risk of cancer metastasis: a study of incident cancers during randomised controlled trials. Lancet. 2012 Apr 28;379(9826):1591-601.
Better progression-free survival but no evidence of an effect on overall survival among people with cancer treated with immune checkpoint inhibitors and low-dose aspirin compared to immune checkpoint inhibitors alone in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 13 observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies²Zhang Y, Chen H et al. The effect of concomitant use of statins, NSAIDs, low-dose aspirin, metformin and beta-blockers on outcomes in patients receiving immune checkpoint inhibitors: a systematic review and meta-analysis. Oncoimmunology. 2021 Aug 2;10(1).

Metastasis: strong evidence of substantially fewer metastases with cancer as a whole among people using aspirin

55% lower risk of metastasis after diagnosis among people using aspirin daily compared to controls, with larger benefits among people with colorectal cancer, in a pooled analysis of 5 very large RCTs³Rothwell PM, Wilson M et al. Effect of daily aspirin on risk of cancer metastasis: a study of incident cancers during randomised controlled trials. Lancet. 2012 Apr 28;379(9826):1591-601.
About 15% lower mortality and 23% lower risk of metastases among people with breast, colorectal, or prostate cancer using aspirin compared to no use, and significantly lower mortality among people with further cancer types, in a pooled analysis of 42 RCTs and observational studies⁴Elwood PC, Morgan G et al. Aspirin in the treatment of cancer: reductions in metastatic spread and in mortality: a systematic review and meta-analyses of published studies. PLoS One. 2016 Apr 20;11(4):e0152402.
Less distant metastasis among people with prostate, breast, lung, or colorectal cancer using aspirin and/or other NSAIDs—predominantly aspirin—before diagnosis (29% lower risk) and after (52% lower risk), and also slightly less lymph node metastasis in a very large meta-analysis of 16 observational studies⁵Zhao X, Xu Z, Li H et al. NSAIDs use and reduced metastasis in cancer patients: results from a meta-analysis. Scientific Reports. 2017 May 12;7(1):1875.

Bladder cancer

Good evidencesignificant effects in one large or several mid-sized and well-designed clinical studies (randomized controlled trials (RCTs) with an appropriate placebo or other strong comparison control or observational studies that control for confounds) (this is the CancerChoices definition; other researchers and studies may define this differently) of moderately better survival among people with bladder cancer using aspirin

Breast cancer

Insufficient (conflicting) findingspreclinical evidence only OR clinical studies with such poor or unclear methodology that no conclusion can be drawn OR conflicting findings across clinical studies with no preponderance of evidence in one direction; conflicting evidence occurs when studies find conflicting effects (positive effect vs no effect or negative effect) with the same treatment and the same general study population (same cancer type, for example) (this is the CancerChoices definition; other researchers and studies may define this differently) indicate that any benefit in breast cancer may depend on the dose or the type of cancer, and in fact substantially higher all-cause mortality is seen among people with postmenopausal hormone receptor-positive breast cancer using low-dose aspirin

Reduced distant metastasis among people with prostate cancer using aspirin and/or other NSAIDs—predominantly aspirin—either before diagnosis (36% lower risk) or after (51% lower risk), with weaker benefit for lymph node metastasis, in a very large meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 16 observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies⁷Zhao X, Xu Z, Li H et al. NSAIDs use and reduced metastasis in cancer patients: results from a meta-analysis. Scientific Reports. 2017 May 12;7(1):1875.
Less metastasis and a weak trendan apparent change due to a therapy, close to but not achieving full statistical significance (this is the CancerChoices definition; other researchers and studies may define this differently toward lower cancer-specific mortality among people using low-dose aspirin after diagnosis in a meta-analysis of observational studies⁸Elwood PC, Morgan G et al. Aspirin in the treatment of cancer: reductions in metastatic spread and in mortality: a systematic review and meta-analyses of published studies. PLoS One. 2016 Apr 20;11(4):e0152402.
No improved survival among people with newly diagnosed breast cancer using low-dose aspirin after diagnosis with an unspecified follow-up time in a very large observational study⁹Mc Menamin ÚC, Cardwell CR, Hughes CM, Murray LJ. Low-dose aspirin use and survival in breast cancer patients: a nationwide cohort study. Cancer Epidemiology. 2017 Apr;47:20-27.
Substantially worse (67% higher) all-cause mortality among people with postmenopausal hormone receptor-positive breast cancer using low-dose (81 mg or less) aspirin compared to no use in a large observational study¹⁰Strasser-Weippl K, Higgins MJ et al. Effects of celecoxib and low-dose aspirin on outcomes in adjuvant aromatase inhibitor-treated patients: CCTG MA.27. Journal of the National Cancer Institute. 2018 Sep 1;110(9):1003-1008.

Colorectal cancer

Good evidence of better colorectal cancer survival among people using aspirin after diagnosis, with preliminary evidencesignificant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect (this is the CancerChoices definition; other researchers and studies may define this differently) that benefit is seen mostly among people with normal prediagnosis body weight

Strong evidence of substantially less risk of metastasis among people with colorectal cancer using aspirin, especially after diagnosis and among people who smoke

Preliminary evidence of slower polyp progression in people with hereditary nonpolyposis colorectal cancer using aspirin

Preliminary evidence of substantially better survival among people with type 2 diabetes and colorectal cancer being treated with metformin and using aspirin

Good evidence of better survival with aspirin use among people with mutated PIK3CA colorectal tumors using aspirin after diagnosis

Preliminary evidence of better overall survival among people with wild-type BRAF tumors, but not mutated BRAF tumors, using aspirin after diagnosis

Preliminary evidence of better survival among people with low CD274 using aspirin regularly

Insufficient (conflicting) evidence of better tumor response to chemoradiation treatment among people with rectal cancer using aspirin

Colorectal cancer as a whole

Survival: good evidence of better survival among people using aspirin after diagnosis, with preliminary evidence that benefit is seen mostly among people with normal prediagnosis body weight

15% lower cancer-specific mortality and 5% lower overall mortality among people with colorectal cancer using aspirin after diagnosis compared to no use during follow-up time of about 3 years in a very large observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods study¹¹Bains SJ, Mahic M et al. Aspirin as secondary prevention in patients with colorectal cancer: an unselected population-based study. Journal of Clinical Oncology. 2016 Jul 20;34(21):2501-8.
56% lower cancer-specific mortality and 25% lower risk of overall mortality among people with colorectal cancer using aspirin after diagnosis, and even lower risks (60% lower cancer-specific and 36% overall mortality) among those who started aspirin use before diagnosis, compared to no aspirin use in a large observational study¹²Hua X, Phipps AI et al. Timing of aspirin and other nonsteroidal anti-inflammatory drug use among patients with colorectal cancer in relation to tumor markers and survival. Journal of Clinical Oncology. 2017 Aug 20;35(24):2806-2813.
40% lower mortality among people beginning regular aspirin use only after diagnosis compared with no aspirin use either before or after diagnosis in a large observational study¹³Figueiredo JC, Jacobs EJ, Newton CC, Guinter MA, Cance WG, Campbell PT. Associations of aspirin and non-aspirin non-steroidal anti-inflammatory drugs with colorectal cancer mortality after diagnosis. NCI: Journal of the National Cancer Institute. 2021 Feb 2:djab008.
37% lower overall mortality among people with colon cancer undergoing adjuvanttreatment applied after initial treatment for cancer, especially to suppress secondary tumor formation chemotherapy and using aspirin compared to no use in a mid-sized observational study¹⁴Ng K, Meyerhardt JA et al. Aspirin and COX-2 inhibitor use in patients with stage III colon cancer. Journal of the National Cancer Institute. 2014 Nov 27;107(1):345.
Moderately lower mortality among people with stage 4 colorectal cancer treated with aspirin after diagnosis, but only among people with normal prediagnosis body mass index and not people with obesity, in a mid-sized observational study¹⁵Davis JS, Chavez JC et al. Association of prediagnosis obesity and postdiagnosis aspirin with survival from stage IV colorectal cancer. JAMA Network Open. 2022 Oct 3;5(10):e2236357.
Substantially longer survival among people with colorectal carcinoma using aspirin after diagnosis compared to no use or use only before diagnosis, although non-users of aspirin were more likely to have stage 3 or stage 4 cancer, in a mid-sized observational study¹⁶Albandar HJ, Markert R, Agrawal S. The relationship between aspirin use and mortality in colorectal cancer. Journal of Gastrointestinal Oncology. 2018 Dec;9(6):1133-1137.
No evidence of an effect on relative survival among people with colorectal cancer and without diabetes and not taking metformin and using aspirin compared to no use in a mid-sized observational study¹⁷De Monte A, Brunetti D et al. Metformin and aspirin treatment could lead to an improved survival rate for Type 2 diabetic patients with stage II and III colorectal adenocarcinoma relative to non-diabetic patients. Molecular and Clinical Oncology. 2018 Mar;8(3):504-512.

Metastasis: strong evidence of substantially less risk of metastasis among people using aspirin, especially after diagnosis and among people who smoke

74% lower risk of distant metastasis among people with colorectal cancer with regular aspirin use compared to controls, with greater benefit among people who smoke, in a pooled analysis of 5 very large RCTsrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects¹⁸Rothwell PM, Wilson M et al. Effect of daily aspirin on risk of cancer metastasis: a study of incident cancers during randomised controlled trials. Lancet. 2012 Apr 28;379(9826):1591-601.

Special populations

Hereditary nonpolyposis: preliminary evidence of slower polyp progression in people with hereditary nonpolyposis colorectal cancer using aspirin

Slower polyp progression in people with hereditary nonpolyposis colorectal cancer using aspirin compared to no use in a review of clinical trials¹⁹Wakeman C, Keenan J et al. Chemoprevention of colorectal neoplasia. ANZ Journal of Surgery. 2017 Dec;87(12):E228-E232.

Diabetes: preliminary evidence of substantially better survival among people with type 2 diabetes and colorectal cancer being treated with metformin and using aspirin

Substantially better relative survival (101% compared to 29%) among people with type 2 diabetes with stage 3 colorectal cancer being treated with metformin and using aspirin compared to no aspirin in a mid-sized observational study²⁰De Monte A, Brunetti D et al. Metformin and aspirin treatment could lead to an improved survival rate for Type 2 diabetic patients with stage II and III colorectal adenocarcinoma relative to non-diabetic patients. Molecular and Clinical Oncology. 2018 Mar;8(3):504-512.

Genetic expression

Good evidence of better survival with aspirin use among people with mutated PIK3CA tumors using aspirin after diagnosis

Preliminary evidence of better overall survival among people with wild-type BRAF tumors, but not mutated BRAF tumors, using aspirin after diagnosis

Preliminary evidence of better survival among people with low CD274 using aspirin regularly

Mutated PIK3CA tumors: good evidence of better survival with aspirin use among people with mutated PIK3CA tumors using aspirin after diagnosis
- 24% lower cancer-specific mortality with low-dose aspirin among people with colon cancer using aspirin after diagnosis, with most of the benefit involving mutated PIK3CA tumors in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of observational studies²¹Elwood PC, Morgan G et al. Aspirin in the treatment of cancer: reductions in metastatic spread and in mortality: a systematic review and meta-analyses of published studies. PLoS One. 2016 Apr 20;11(4):e0152402.
- 16% lower overall mortality (22% lower with colon cancer and 10% lower with rectal cancer) but not cancer-specific mortality among people using aspirin after diagnosis but not before diagnosis, and only in people mutated PIK3CA tumors and positive for COX-2 expression—which influences tumor invasiveness and inflammatory responses—in a meta-analysis of observational studies²²Li P, Wu H et al. Aspirin use after diagnosis but not prediagnosis improves established colorectal cancer survival: a meta-analysis. Gut. 2015 Sep;64(9):1419-25. and a mid-sized observational study²³Frouws MA, Reimers MS et al. The influence of BRAF and KRAS mutation status on the association between aspirin use and survival after colon cancer diagnosis.PLoS One. 2017 Jan 26;12(1):e0170775.
- 82% lower cancer-specific mortality and 46% overall mortality among people with mutated-PIK3CA colorectal cancers, but not wild-type PIK3CA, using aspirin regularly after diagnosis compared to no aspirin use in a mid-sized observational study²⁴Liao X, Lochhead P et alS. Aspirin use, tumor PIK3CA mutation, and colorectal-cancer survival. New England Journal of Medicine. 2012 Oct 25;367(17):1596-606.
- Better overall mortality and a weak trendan apparent change due to a therapy, close to but not achieving full statistical significance (this is the CancerChoices definition; other researchers and studies may define this differently toward better cancer-specific mortality among people with mutated-PIK3CA colorectal cancers, but not wild-type PIK3CA, using aspirin after diagnosis in a meta-analysis of observational studies²⁵Paleari L, Puntoni M et al. PIK3CA mutation, aspirin use after diagnosis and survival of colorectal cancer. a systematic review and meta-analysis of epidemiological studies. Clinical Oncology (Royal College of Radiologists, Great Britain). 2016 May;28(5):317-26.
- Better overall survival among people with mutated-PIK3CA colorectal cancers, but not wild-type PIK3CA, using aspirin regularly after diagnosis in a meta-analysis of 3 observational studies²⁶Mei ZB, Duan CY, Li CB, Cui L, Ogino S. Prognostic role of tumor PIK3CA mutation in colorectal cancer: a systematic review and meta-analysis. Annals of Oncology. 2016 Oct;27(10):1836-48.
Wild-type BRAF tumors: preliminary evidence of better overall survival among people with wild-type BRAF tumors, but not mutated BRAF tumors, using aspirin after diagnosis
- Better overall survival among people with wild-type BRAF tumors, but not mutated BRAF tumors, using aspirin compared to no use in a mid-sized observational study²⁷Frouws MA, Reimers MS et al. The influence of BRAF and KRAS mutation status on the association between aspirin use and survival after colon cancer diagnosis. PLoS One. 2017 Jan 26;12(1):e0170775.
Low CD274 (PDL1): preliminary evidence of better survival among people with low CD274 using aspirin regularly
- 84% lower cancer-specific mortality among people with colorectal cancer with low CD274 (PDL1) using aspirin regularly compared to no use, but no evidence of an effect on people with high CD274 in a mid-sized observational study²⁸Hamada T, Cao Y et al. Aspirin use and colorectal cancer survival according to tumor CD274 (Programmed Cell Death 1 Ligand 1) expression status. Journal of Clinical Oncology. 2017 Jun 1;35(16):1836-1844.

Rectal cancer

Insufficient (conflicting) evidence of better tumor response to chemoradiation treatment among people with rectal cancer using aspirin

Improved 5-year progression-free and overall survival, lower risk of developing metastasis, decreased tumor size (tumor downstaging), and pathological response, but no evidence of an effect on local relapse among people with rectal cancer using aspirin during chemoradiation in a mid-sized observational study²⁹Restivo A, Cocco IM et al. Aspirin as a neoadjuvant agent during preoperative chemoradiation for rectal cancer. British Journal of Cancer. 2015 Oct 20;113(8):1133-9.
No improvements in pathological complete response rate or bladder or rectal toxicity among people with rectal cancer receiving neo-adjuvanttherapy used before a main treatment, such as chemotherapy, radiation therapy, and hormone therapy before surgery long-course radiation therapy, with most also receiving concurrent chemotherapy, and using aspirin compared to no use in a mid-sized observational study³⁰Hardie C, Jung Y, Jameson M. Effect of statin and aspirin use on toxicity and pathological complete response rate of neo-adjuvant chemoradiation for rectal cancer. Asia-Pacific Journal of Clinical Oncology. 2016 Jun;12(2):167-73.

Gastrointestinal cancer

Colorectal cancer is listed separately.

No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on survival among people with esophageal or gastrointestinal cancer using low-dose aspirin after diagnosis in a combined analysis of studies

Modest evidencesignificant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observational studies), or several small studies aggregated into a meta-analysis (this is the CancerChoices definition; other researchers and studies may define this differently) of better survival among people with hepatobiliary tract cancer using aspirin regularly after diagnosis

Head and neck cancer

No evidence of an effect on survival among people with head and neck cancer treated with aspirin in a combined analysis of studies

Preliminary evidence of better survival and smaller tumor volume among people with head and neck cancer with PIK3CA mutations or amplification using NSAIDs—predominantly aspirin—after diagnosis

Lymphoma

No evidence of an effect on response rate, event-free survival, or overall survival after chemoimmunotherapy among people with diffuse large B-cell lymphoma treated with aspirin in a mid-sized study

Ovarian cancer

No evidence of an effect on overall survival among people with ovarian cancer treated with aspirin

Prostate cancer

Modest (somewhat conflicting) evidence of better survival among people using aspirin after diagnosis

Modest evidence (due to inclusion of non-aspirin nonsteroidal anti-inflammatory drugs, NSAIDs) of lower metastasis among people with prostate cancer using aspirin, with a stronger effect with use after diagnosis

28% lower overall mortality and 32% lower cancer-specific mortality (lethal prostate cancer) among men with prostate cancer using aspirin regularly compared to no use in a very large RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects³⁸Downer MK, Allard CB et al. Regular aspirin use and the risk of lethal prostate cancer in the Physicians’ Health Study. European Urology. 2017 Nov;72(5):821-827.
Reduced distant metastasis among people with prostate cancer using aspirin and/or other NSAIDs—predominantly aspirin—either before diagnosis (13% lower risk) or after (52% lower risk), with weaker benefit for lymph node metastasis, in a very large meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 16 observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies³⁹Zhao X, Xu Z, Li H et al. NSAIDs use and reduced metastasis in cancer patients: results from a meta-analysis. Scientific Reports. 2017 May 12;7(1):1875.
Better overall survival but not cancer-specific survival among people with prostate cancer using aspirin after diagnosis in a large observational study⁴⁰Zhou CK, Daugherty SE et al. Do aspirin and other NSAIDs confer a survival benefit in men diagnosed with prostate cancer? A pooled analysis of NIH-AARP and PLCO cohorts. Cancer Prevention Research (Phila). 2017 Jul;10(7):410-420.
No benefit on lethal prostate cancer among people taking fewer than 2 to 6 or more aspirin tablets per week after a prostate cancer diagnosis compared to no use in a large observational study⁴¹Dhillon PK, Kenfield SA, Stampfer MJ, Giovannucci EL, Chan JM. Aspirin use after a prostate cancer diagnosis and cancer survival in a prospective cohort. Cancer Prevention Research (Philadelphia). 2012 Oct;5(10):1223-8.

Optimizing your body terrain

Does aspirin promote an environment within your body that is less supportive of cancer development, growth, or spread? We present the evidence.

See Optimizing Your Body Terrain ›

Find medical professionals who specialize in managing body terrain factors: Finding Integrative Oncologists and Other Practitioners ›

Inflammation

Managing side effects and promoting wellness

Is aspirin linked to fewer or less severe side effects or symptoms? Is it linked to less toxicity from cancer treatment? Does it support your quality of life or promote general well-being? We present the evidence.

Pain

Strong evidenceconsistent, significant effects in several large (or at least one very large) well designed clinical studies or at least two meta-analyses of clinical studies of moderate or better quality (or one large meta-analysis) finding similar results (this is the CancerChoices definition; other researchers and studies may define this differently) of less chronic cancer pain among people using codeine plus aspirin

Symptoms not specific to cancer

Cardiovascular side effects: preliminary evidencesignificant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect (this is the CancerChoices definition; other researchers and studies may define this differently) of fewer vascular disease events, not specific to people with cancer, among people using aspirin

Reducing cancer risk

Is aspirin linked to lower risks of developing cancer or of recurrence? We present the evidence.

Cancer as a whole

Insufficient (conflicting) evidencepreclinical evidence only OR clinical studies with such poor or unclear methodology that no conclusion can be drawn OR conflicting findings across clinical studies with no preponderance of evidence in one direction; conflicting evidence occurs when studies find conflicting effects (positive effect vs no effect or negative effect) with the same treatment and the same general study population (same cancer type, for example) (this is the CancerChoices definition; other researchers and studies may define this differently) of lower cancer-related mortality among people without cancer at baseline using aspirin regularly

Good evidencesignificant effects in one large or several mid-sized and well-designed clinical studies (randomized controlled trials (RCTs) with an appropriate placebo or other strong comparison control or observational studies that control for confounds) (this is the CancerChoices definition; other researchers and studies may define this differently) of slightly lower risk of cancer as a whole among people using aspirin

Strong evidenceconsistent, significant effects in several large (or at least one very large) well designed clinical studies or at least two meta-analyses of clinical studies of moderate or better quality (or one large meta-analysis) finding similar results (this is the CancerChoices definition; other researchers and studies may define this differently) of lower risk of distant metastasis among people without cancer at baseline using aspirin regularly, with greater benefit among people who smoke

Cancer mortality: insufficient (conflicting) evidence of lower cancer-related mortality among people without cancer at baseline using aspirin regularly, with evidence that the effect may be mainly among people developing adenocarcinomas

34% lower cancer-related mortality among people without cancer at baseline using aspirin daily for 5 years or longer compared to no use in a large pooled analysis of randomized trials⁴⁶Rothwell PM, Fowkes FG et al. Effect of daily aspirin on long-term risk of death due to cancer: analysis of individual patient data from randomised trials. Lancet. 2011 Jan 1;377(9759):31-41.
35% lower risk of fatal adenocarcinoma with daily aspirin use compared to controls, with greater benefit among people who smoke, but no evidence of an effect on other cancer types in a pooled analysis of 5 very large RCTsrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects⁴⁷Rothwell PM, Wilson M et al. Effect of daily aspirin on risk of cancer metastasis: a study of incident cancers during randomised controlled trials. Lancet. 2012 Apr 28;379(9826):1591-601.

Cancer risk: good evidence of slightly lower risk of cancer as a whole among people using aspirin

11% lower risk of cancer as a whole among people using aspirin compared to no aspirin in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 218 observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies⁴⁸Qiao Y, Yang T et al. Associations between aspirin use and the risk of cancers: a meta-analysis of observational studies. BMC Cancer. 2018 Mar 13;18(1):288.

Metastasis: strong evidence of lower risk of distant metastasis among people without cancer at baseline using aspirin regularly, with greater benefit among people who smoke

36% lower risk of distant metastasis, either at cancer diagnosis or after, among people without cancer at baseline using aspirin regularly compared to controls, with greater benefit among people who smoke, in a pooled analysis of 5 very large RCTs⁴⁹Rothwell PM, Wilson M et al. Effect of daily aspirin on risk of cancer metastasis: a study of incident cancers during randomised controlled trials. Lancet. 2012 Apr 28;379(9826):1591-601.

Bladder cancer

No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on risk of bladder cancer among people using aspirin in a combined analysis of observational studies

Brain cancer

No evidence of an effect on risk of brain cancer among people using aspirin in a combined analysis of observational studies

Breast cancer

No evidence of an effect on recurrence among people with high-risk, HER2-negative breast cancer using aspirin in a very large study

Good evidence of lower risk of some subtypes of breast cancer—hormone receptor positive tumors, in situ breast tumors—or among postmenopausal women, but not of breast cancer as a whole among people regularly using aspirin

Recurrence: no evidence of an effect on recurrence among people with high-risk, HER2-negative breast cancer using aspirin in a very large study

No evidence of an effect on risk of recurrence (invasive disease-free survival) among people with high-risk, HER2-negative breast cancer taking 300 mg aspirin a day compared to placebo in a very large RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects⁵³Chen WY. A randomized phase III, double-blinded, placebo-controlled trial of aspirin as adjuvant therapy for breast cancer (A011502): The Aspirin after Breast Cancer (ABC) Trial. ASCO Plenary Series: February 2022 Session. Viewed February 17, 2022.

Cancer risk

No evidence of an effect on risk of breast cancer among healthy women aged 45 years or older taking aspirin every other day in a very large study

Good evidence of lower risk of some subtypes of breast cancer—hormone receptor positive tumors or in situ breast tumors—or among postmenopausal women regularly using aspirin

No evidence of an effect on risk of breast cancer at 16 years after initiation among healthy women aged 45 years or older taking 100 mg aspirin every other day for 8–10 years compared to placebo in a very large RCT⁵⁴Cook NR, Lee IM, Zhang SM, Moorthy MV, Buring JE. Alternate-day, low-dose aspirin and cancer risk: long-term observational follow-up of a randomized trial. Annals of Internal Medicine. 2013 Jul 16;159(2):77-85.
9% lower risk of breast cancer among people using aspirin compared to no use, with significant benefits regarding hormone receptor positive tumors, in situ breast tumors, postmenopausal women, and with use more than 4 times a week or for more than 10 years, in a very large meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies⁵⁵Cao Y, Tan A. Aspirin might reduce the incidence of breast cancer: an updated meta-analysis of 38 observational studies. Medicine (Baltimore). 2020 Sep 18;99(38):e21917.
Slightly lower risk of breast cancer among people using aspirin compared to no aspirin in a meta-analysis of 33 observational studies⁵⁶Qiao Y, Yang T et al. Associations between aspirin use and the risk of cancers: a meta-analysis of observational studies. BMC Cancer. 2018 Mar 13;18(1):288.
Lower risks of cancer mortality and metastatic cancer among people without cancer at baseline using aspirin regularly in pooled data from 5 observational studies⁵⁷Chen WY, Holmes MD. Role of aspirin in breast cancer survival. Current Oncology Reports. 2017 Jul;19(7):48.
Lower risk of in situ breast tumors or hormone receptor-positive tumors, or of breast cancer among postmenopausal women using aspirin compared to no use in a meta-analysis of observational studies⁵⁸Zhong S, Chen L et al. Aspirin use and risk of breast cancer: systematic review and meta-analysis of observational studies. Cancer Epidemiology, Biomarkers & Prevention. 2015 Nov;24(11):1645-55.
39% lower risk of breast cancer among people using aspirin compared to no use in a pooled analysis of 4 observational studies⁵⁹Harris RE, Beebe J, Alshafie GA. Reduction in cancer risk by selective and nonselective cyclooxygenase-2 (COX-2) inhibitors. Journal of Experimental Pharmacology. 2012 Aug 10;4:91-6.
No reduced risk across all types of breast cancer among individuals aged 65 years or older using aspirin compared to no use in a large observational study⁶⁰Loomans-Kropp HA, Pinsky P, Umar A. Evaluation of aspirin use with cancer incidence and survival among older adults in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. JAMA Network Open. 2021 Jan 4;4(1):e2032072.; also see cautions about aspirin use in older adults in Safety and precautions ›

Colorectal cancer

Good evidence of substantially lower risk of colorectal cancer recurrence among people using aspirin regularly

Strong evidence of lower risk of colorectal cancer among people using aspirin regularly

Strong evidence of lower risk of cancer or of polyp progression among people with higher risk due to hereditary, family, or personal history using aspirin regularly

Good evidence of lower risk of recurrence of adenomas or polyps among people using aspirin

Preliminary evidencesignificant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect (this is the CancerChoices definition; other researchers and studies may define this differently) of reduced risk only when aspirin use was started before age 65

Recurrence: good evidence of substantially lower risk of recurrence among people using aspirin regularly

89% lower risk of recurrence among people with colorectal cancer with PIK3CA mutations using low-dose aspirin regularly after diagnosis, but no evidence of an effect among people without mutations, compared to no use in an observation within a large trial⁶¹Domingo E, Church DN et al. Evaluation of PIK3CA mutation as a predictor of benefit from nonsteroidal anti-inflammatory drug therapy in colorectal cancer. Journal of Clinical Oncology. 2013 Dec 1;31(34):4297-305.
32–49% lower risk of relapse or recurrence (better disease-free survival and recurrence-free survival, respectively) at 5 years among people with colon cancer enrolled in an adjuvanttreatment applied after initial treatment for cancer, especially to suppress secondary tumor formation chemotherapy trial using 5 or more tablets per week of aspirin compared to no use in a mid-sized observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods study⁶²Ng K, Meyerhardt JA et al. Aspirin and COX-2 inhibitor use in patients with stage III colon cancer. Journal of the National Cancer Institute. 2014 Nov 27;107(1):345.

Colorectal cancer risk

Strong evidence of lower risk of colorectal cancer among people using aspirin regularly

Strong evidence of lower risk of cancer or of polyp progression among people with higher risk due to hereditary, family, or personal history using aspirin regularly

Good evidence of lower risk of recurrence of adenomas or polyps among people using aspirin

Preliminary evidence of reduced risk only when aspirin use was started before age 65

Risk in the general population: strong evidence of lower risk of colorectal cancer among people using aspirin regularly

24% lower risk of colon cancer and 35% lower colon cancer mortality but no evidence of an effect on rectal cancer at 20 years among people taking 75-300 mg aspirin daily for an average of 6 years compared to controls, and with larger benefit for both colon and rectal cancer with treatment longer than 5 years in a large meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 4 RCTsrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects⁶³Rothwell PM, Wilson M et al. Long-term effect of aspirin on colorectal cancer incidence and mortality: 20-year follow-up of five randomised trials. Lancet. 2010 Nov 20;376(9754):1741-50.
21% lower risk of colorectal cancer among people using aspirin compared to no aspirin in a meta-analysis of 39 observational studies⁶⁴Qiao Y, Yang T et al. Associations between aspirin use and the risk of cancers: a meta-analysis of observational studies. BMC Cancer. 2018 Mar 13;18(1):288.
26% lower risk of colorectal cancer among people using aspirin 5 years or more—and especially 10 years or more—in a pooled analysis of RCTs, but only with a latency of 10 years or more, and only with 300 mg or more of aspirin a day in a very large analysis of observational studies⁶⁵Flossmann E, Rothwell PM; British Doctors Aspirin Trial and the UK-TIA Aspirin Trial. Effect of aspirin on long-term risk of colorectal cancer: consistent evidence from randomised and observational studies. Lancet. 2007 May 12;369(9573):1603-13.
29% lower colorectal cancer-related mortality among people aged 65 years and older without cancer at baseline using aspirin 3 times a week compared to no use, with even lower mortality among those with body mass index between 25 and 29.9 (overweight), with a follow up of about 12 years in a very large observational study⁶⁶Loomans-Kropp HA, Pinsky P, Cao Y, Chan AT, Umar A. Association of aspirin use with mortality risk among older adult participants in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. JAMA Network Open. 2019 Dec 2;2(12):e1916729.
31% lower risk of colorectal cancer-specific mortality and 27% lower risk of distant metastases at the time of diagnosis among people without cancer at baseline using aspirin more than 15 times per month long-term before diagnosis in a large observational study⁶⁷Figueiredo JC, Jacobs EJ, Newton CC, Guinter MA, Cance WG, Campbell PT. Associations of aspirin and non-aspirin non-steroidal anti-inflammatory drugs with colorectal cancer mortality after diagnosis. NCI: Journal of the National Cancer Institute. 2021 Feb 2:djab008.
27% lower risk of colorectal cancer among people using aspirin regularly compared to no use, with more benefit at 325 mg/day compared to 75–100 mg/day in a large meta-analysis of 45 observational studies⁶⁸Bosetti C, Santucci C, Gallus S, Martinetti M, La Vecchia C. Aspirin and the risk of colorectal and other digestive tract cancers: an updated meta-analysis through 2019. Annals of Oncology. 2020;S0923-7534(20)36073-7.
19% lower risk of colorectal serrated polyps among people using aspirin compared to no use in a meta-analysis of observational or interventional studies⁶⁹Bailie L, Loughrey MB, Coleman HG. Lifestyle risk factors for serrated colorectal polyps: a systematic review and meta-analysis. Gastroenterology. 2017 Jan;152(1):92-104.
16% lower risk of cancer in the distal colon and 26% lower risk in the rectum among people using aspirin daily compared to non-users in a very large observational study⁷⁰Ruder EH, Laiyemo AO et al. Non-steroidal anti-inflammatory drugs and colorectal cancer risk in a large, prospective cohort. American Journal of Gastroenterology. 2011 Jul;106(7):1340-50.
27% lower risk of colorectal cancer among people with continuous long-term use (5 years or more) of low-dose aspirin compared to no use in a very large observational study⁷¹Friis S, Riis AH, Erichsen R, Baron JA, Sørensen HT. Low-dose aspirin or nonsteroidal anti-inflammatory drug use and colorectal cancer risk: a population-based, case-control study. Annals of Internal Medicine. 2015 Sep 1;163(5):347-55.
67% lower risk of colon cancer among people using aspirin compared to no use in a mid-sized observational study⁷²Harris RE, Beebe J, Alshafie GA. Reduction in cancer risk by selective and nonselective cyclooxygenase-2 (COX-2) inhibitors. Journal of Experimental Pharmacology. 2012 Aug 10;4:91-6.

Risk of adenomas or polyps: strong evidence of lower risk of colorectal adenomas or advanced lesions among people using aspirin, but varying by the duration of aspirin use

Lower risk of colorectal adenomas but only a weak trendan apparent change due to a therapy, close to but not achieving full statistical significance (this is the CancerChoices definition; other researchers and studies may define this differently toward fewer advanced lesions at 3 years past baseline, lower risk of advanced lesions but not adenomas at 5 years, and only a weak trend toward lower risk of advanced lesions after more than 5 years among healthy people using aspirin daily compared to placebo in a meta-analysis of 11 RCTs⁷³Ghaddaf AA, Aziz M et al. Influence of aspirin on prevention of colorectal cancer: an updated systematic review and meta-analysis of randomized controlled trials. International Journal of Colorectal Disease. 2021 Aug;36(8):1711-1722.

People with higher risk due to hereditary, family, or personal history: strong evidence of lower risk of cancer or of polyp progression among people with higher risk due to hereditary, family, or personal history using aspirin regularly

35% lower risk of colorectal cancer among people with Lynch syndrome, a hereditary condition linked to higher incidence of colorectal cancer, using 600 mg aspirin daily compared to placebo with a 10- to 20-year follow up in a large RCT⁷⁴Burn J, Sheth H et al; CAPP2 Investigators. Cancer prevention with aspirin in hereditary colorectal cancer (Lynch syndrome), 10-year follow-up and registry-based 20-year data in the CAPP2 study: a double-blind, randomised, placebo-controlled trial. Lancet. 2020 Jun 13;395(10240):1855-1863.
Lower risk of colorectal cancer among people using aspirin regularly compared to no use, limited to individuals with a specific T allele, in an umbrella review of systematic reviews and meta-analyses of observational studies⁷⁵Yang T, Li X et al. International Journal of Cancer. Gene-environment interactions and colorectal cancer risk: an umbrella review of systematic reviews and meta-analyses of observational studies. 2019 Nov 1;145(9):2315-2329.
Slower polyp progression in people with hereditary nonpolyposis colorectal cancer using aspirin compared to no use in a review of clinical trials⁷⁶Wakeman C, Keenan J et al. Chemoprevention of colorectal neoplasia. ANZ Journal of Surgery. 2017 Dec;87(12):E228-E232.

Recurrence of adenomas or polyps: good evidence of lower risk of recurrence of adenomas or polyps among people using aspirin

17% lower risk of recurrent adenomas among people with a history of colorectal cancer or adenomas using any dose of aspirin compared to placebo or no use in a meta-analysis of RCTs⁷⁷Veettil SK, Lim KG et al. Effects of aspirin and nonaspirin nonsteroidal anti-inflammatory drugs on the incidence of recurrent colorectal adenomas: a systematic review with meta-analysis and trial sequential analysis of randomized clinical trials. BMC Cancer. 2017 Nov 14;17(1):763.
6.7% absolute lower risk of colorectal adenomas among individuals with a history of these lesions with aspirin use of various doses compared to no use in a meta-analysis of RCTs⁷⁸Cole BF, Logan RF et al. Aspirin for the chemoprevention of colorectal adenomas: meta-analysis of the randomized trials. Journal of the National Cancer Institute. 2009 Feb 18;101(4):256-66.
Lower adenoma recurrence after 1 year but not 4 years among people with colorectal adenomas who had not been regular users of aspirin with either of 2 doses of lysine acetylsalicylate (a soluble salt of aspirin) compared to no use in a mid-sized RCT⁷⁹Benamouzig R, Uzzan B et al; Association pour la Prévention par l’Aspirine du Cancer Colorectal Study Group (APACC). Prevention by daily soluble aspirin of colorectal adenoma recurrence: 4-year results of the APACC randomised trial. Gut. 2012 Feb;61(2):255-61.
Lower risk of colorectal polyps among people with a history of more than 100 adenomatous polyps in the large intestine, without a history of colectomy, with aspirin use compared to placebo in a mid-sized RCT⁸⁰Ishikawa H, Mutoh M et al. Chemoprevention with low-dose aspirin, mesalazine, or both in patients with familial adenomatous polyposis without previous colectomy (J-FAPP Study IV): a multicentre, double-blind, randomised, two-by-two factorial design trial. Lancet Gastroenterology and Hepatology. 2021 Jun;6(6):474-481.

Older adults: preliminary evidence of reduced risk only when aspirin use was started before age 65; also see cautions about aspirin use in older adults in Safety and precautions ›

No reduced risk among individuals aged 65 years or older using aspirin compared to no use in a large observational study⁸¹Loomans-Kropp HA, Pinsky P, Umar A. Evaluation of aspirin use with cancer incidence and survival among older adults in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. JAMA Network Open. 2021 Jan 4;4(1):e2032072.
20% lower risk of colorectal cancer among people aged 70 or more using aspirin regularly compared to irregular use, but only when begun at a younger age⁸²Guo CG, Ma W et al. Aspirin use and risk of colorectal cancer among older adults. JAMA Oncology. 2021 Mar 1;7(3):428-435.

Gastrointestinal cancer

Colorectal cancer and pancreatic cancer are listed separately.

Strong evidence of lower risk of several types of gastrointestinal cancer, including esophageal, stomach, gallbladder, and liver/bile duct hepatobiliary tract cancers, among people using aspirin

Modest evidencesignificant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observational studies), or several small studies aggregated into a meta-analysis (this is the CancerChoices definition; other researchers and studies may define this differently) of lower secondary primary cancer, especially esophageal cancer and stomach cancer, among people with head and neck cancer using aspirin

No evidence of an effect on risk of esophageal cancer or stomach cancer among individuals aged 65 years or older using aspirin in a large study

Strong evidence of lower risk of several types of gastrointestinal cancer, including esophageal, stomach, gallbladder, and liver/bile duct hepatobiliary tract cancers, among people using aspirin

Esophageal cancer: good evidence of lower risk of adenocarcinoma of the esophagus and gastric cardia or of squamous-cell esophageal cancer among people using aspirin regularly

25% lower risk of esophageal cancer among people using aspirin compared to no aspirin in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 12 observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies⁸³Qiao Y, Yang T et al. Associations between aspirin use and the risk of cancers: a meta-analysis of observational studies. BMC Cancer. 2018 Mar 13;18(1):288.
Lower risk of adenocarcinoma of the esophagus and gastric cardia (39% lower risk) or of squamous-cell esophageal cancer (33% lower risk) among people using aspirin regularly compared to no use in a large meta-analysis of 13 observational studies⁸⁴Bosetti C, Santucci C, Gallus S, Martinetti M, La Vecchia C. Aspirin and the risk of colorectal and other digestive tract cancers: an updated meta-analysis through 2019. Annals of Oncology. 2020;S0923-7534(20)36073-7.

Liver, bile duct, or gallbladder cancer: good evidence of lower risk of liver, bile duct, or gallbladder cancer among people using aspirin

39% lower risk of liver cancer (hepatocellular carcinoma) among people using aspirin compared to other people in a very large meta-analysis of observational studies⁸⁵Memel ZN, Arvind A et al. Aspirin use is associated with a reduced incidence of hepatocellular carcinoma: a systematic review and meta-analysis. Hepatology Communications. 2020 Nov 13;5(1).
44% lower risk of bile duct cancer (cholangiocarcinoma) among people using aspirin compared to no use in a very large meta-analysis of observational studies⁸⁶Lapumnuaypol K, Tiu A et al. Effects of aspirin and non-steroidal anti-inflammatory drugs on the risk of cholangiocarcinoma: a meta-analysis. QJM. 2019 Jun 1;112(6):421-427.
A weak trendan apparent change due to a therapy, close to but not achieving full statistical significance (this is the CancerChoices definition; other researchers and studies may define this differently toward lower risk of hepato-biliary cancer among people using aspirin compared to no aspirin in a meta-analysis of 7 observational studies⁸⁷Qiao Y, Yang T et al. Associations between aspirin use and the risk of cancers: a meta-analysis of observational studies. BMC Cancer. 2018 Mar 13;18(1):288.
38% lower risk of hepatobiliary tract cancer among people using aspirin regularly compared to no use in a large meta-analysis of 5 observational studies⁸⁸Bosetti C, Santucci C, Gallus S, Martinetti M, La Vecchia C. Aspirin and the risk of colorectal and other digestive tract cancers: an updated meta-analysis through 2019. Annals of Oncology. 2020;S0923-7534(20)36073-7.
31% lower risk of liver cancer over almost 8 years among people with chronic viral hepatitis using low-dose (160 mg or less) aspirin without raising risk of gastrointestinal bleeding in a very large observational study⁸⁹Simon TG, Duberg AS et al. Association of aspirin with hepatocellular carcinoma and liver-related mortality. New England Journal of Medicine. 2020 Mar 12;382(11):1018-1028.
Substantially lower risk of gallbladder cancer among people using aspirin compared to no use in a large observational study⁹⁰Prasai K, Tella SH et al. Aspirin and statin use and the risk of gallbladder cancer. Cancers (Basel). 2021 Mar 9;13(5):1186.

Stomach cancer: good evidence of lower risk of stomach cancer among people using aspirin

36% lower risk of stomach cancer among people using aspirin regularly compared to no use in a large meta-analysis of 14 observational studies⁹¹Bosetti C, Santucci C, Gallus S, Martinetti M, La Vecchia C. Aspirin and the risk of colorectal and other digestive tract cancers: an updated meta-analysis through 2019. Annals of Oncology. 2020;S0923-7534(20)36073-7.
25% lower risk of stomach cancer among people using aspirin compared to no aspirin in a meta-analysis of 17 observational studies⁹²Qiao Y, Yang T et al. Associations between aspirin use and the risk of cancers: a meta-analysis of observational studies. BMC Cancer. 2018 Mar 13;18(1):288.

People with head and neck cancer: modest evidence of lower secondary primary cancer, especially esophageal cancer and stomach cancer, among people with head and neck cancer using aspirin

25% lower risk of secondary primary cancer, especially esophageal cancer and stomach cancer, among people with head and neck cancer using aspirin compared to no use in a very large observational study⁹³Lin YS, Yeh CC et al. Aspirin associated with risk reduction of secondary primary cancer for patients with head and neck cancer: a population-based analysis. PLoS One. 2018 Aug 22;13(8):e0199014.

Older adults: no evidence of an effect on risk of esophageal cancer or stomach cancer among individuals aged 65 years or older using aspirin in a large study

No reduced risk of esophageal cancer or stomach cancer among individuals aged 65 years or older using aspirin compared to no use in a large observational study⁹⁴Loomans-Kropp HA, Pinsky P, Umar A. Evaluation of aspirin use with cancer incidence and survival among older adults in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. JAMA Network Open. 2021 Jan 4;4(1):e2032072.

Gynecological cancers

Ovarian cancer is listed separately.

Good evidence of slightly lower risk of endometrial cancer among people using aspirin

No evidence of an effect on risk of uterine cancer among people aged 65 or older using aspirin in a large study

Head and neck cancer

No evidence of an effect on risk of head and neck cancer among people using aspirin in several combined analyses of studies

Kidney cancer

No evidence of an effect on risk of kidney cancer among people using aspirin in a combined analysis of studies

Leukemia

No evidence of an effect on risk of leukemia among people using aspirin in a combined analysis of studies

Lung cancer

Good evidence of lower risk of lung cancer with aspirin use, except among people aged 65 years or older

Lymphoma

No evidence of an effect on risk of lymphoma among people using aspirin in a combined analysis of studies

Melanoma and other skin cancers

Weak evidenceone or more case studies, supported by animal evidence OR small treatment effects of limited clinical significance OR studies with no controls OR weak trends of effects (this is the CancerChoices definition; other researchers and studies may define this differently) of slightly lower risk of skin cancer among people using aspirin

Ovarian cancer

Good evidence of lower risk of ovarian cancer among people using aspirin, including people with risk factors for ovarian cancer

Pancreatic cancer

Good evidence of lower risk of pancreatic cancer with aspirin use, but not among older adults

Prostate cancer

Good evidence of lower risk of prostate cancer, especially of advanced or lethal cancer, among people using aspirin

32% lower risk of lethal prostate cancer among healthy male physicians using aspirin regularly compared to never users in a very large RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects¹¹²Downer MK, Allard CB et al. Regular aspirin use and the risk of lethal prostate cancer in the Physicians’ Health Study. European Urology. 2017 Nov;72(5):821-827.
Slightly lower risk of prostate cancer among people using aspirin compared to no aspirin in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 28 observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies¹¹³Qiao Y, Yang T et al. Associations between aspirin use and the risk of cancers: a meta-analysis of observational studies. BMC Cancer. 2018 Mar 13;18(1):288.
10% lower risk of prostate cancer among people using aspirin regularly compared to no use in a meta-analysis of observational studies¹¹⁴Bosetti C, Rosato V, Gallus S, Cuzick J, La Vecchia C. Aspirin and cancer risk: a quantitative review to 2011. Annals of Oncology. 2012 Jun;23(6):1403-15.
46% lower risk of prostate cancer among people using aspirin compared to no use in a pooled analysis of 2 observational studies¹¹⁵Harris RE, Beebe J, Alshafie GA. Reduction in cancer risk by selective and nonselective cyclooxygenase-2 (COX-2) inhibitors. Journal of Experimental Pharmacology. 2012 Aug 10;4:91-6.
Lower risk of prostate cancer among men with a negative biopsy using aspirin compared to no use in a large observational study¹¹⁶Vidal AC, Howard LE et al. Aspirin, NSAIDs, and risk of prostate cancer: results from the REDUCE study. Clinical Cancer Research. 2015;21(4):756-762.
Better overall survival but not prostate cancer-specific survival among people without cancer at baseline using aspirin before diagnosis compared to no use in a large observational study¹¹⁷Zhou CK, Daugherty SE et al. Do aspirin and other NSAIDs confer a survival benefit in men diagnosed with prostate cancer? A pooled analysis of NIH-AARP and PLCO cohorts. Cancer Prevention Research (Phila). 2017 Jul;10(7):410-420.
Substantially lower risk of advanced prostate cancer (65% lower for T3 and 78% lower for T4) and 74–83% lower risk of recurrence among men of African-American descent using aspirin 3 or more years compared to no use in a large observational study¹¹⁸Smith CJ, Dorsey TH et al. Aspirin use reduces the risk of aggressive prostate cancer and disease recurrence in African-American men. Cancer Epidemiology, Biomarkers & Prevention. 2017 Jun;26(6):845-853.

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Nancy Hepp, MS

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Last update: January 20, 2024

Last full literature review: September 2021

CancerChoices provides information about integrative in cancer care, a patient-centered approach combining the best of conventional care, self care and evidence-informed complementary care in an integrated plan cancer care. We review complementaryin cancer care, complementary care involves the use of therapies intended to enhance or add to standard conventional treatments; examples include supplements, mind-body approaches such as yoga or psychosocial therapy, and acupuncture therapies and self-care lifestyle actions and behaviors that may impact cancer outcomes; examples include eating health-promoting foods, limiting alcohol, increasing physical activity, and managing stress practices to help patients and professionals explore and integrate the best combination of conventionalthe cancer care offered by conventionally trained physicians and most hospitals; examples are chemotherapy, surgery, and radiotherapy and complementary therapies and practices for each person.

Our staff have no financial conflicts of interest to declare. We receive no funds from any manufacturers or retailers gaining financial profit by promoting or discouraging therapies mentioned on this site.

Aspirin

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Keep reading about aspirin

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Barry D. Elson, MD

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References
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