Your Breast Cancer Handbook

Self-care practices and complementary therapies for reducing your risk of breast cancer

Self-care practices are the foundation of risk reduction, and some complementary therapies may also reduce risk. Please also review the Safety and precautions page within the linked reviews for guidance on safe use. We recommend supervision from a medical professional trained in the use of complementary therapies. 

Details of the evidence supporting the statements are available through the image links.

Strong, good, or modest evidence of benefit for reducing cancer risk

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) indicates confidence that the practice or therapy has an effect as noted. 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) indicates that the practice or therapy is linked to the outcomes described with reasonable certainty. 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) means the practice or therapy may be linked to the outcomes described, but with a lower degree of certainty.

The evidence for these effects is described in the reviews available through the image links.

Eating Well: strong to modest evidence

• Moderately lower risk of breast cancer among people eating more vegetables, especially cruciferous vegetables (broccoli family) or carrots (modest evidence)
• Moderately lower risk of breast cancer among people eating fruits and vegetables (modest evidence)
• Moderately lower risk of breast cancer among people eating fruits and vegetables (modest evidence)
• Moderately lower risk of breast cancer among Asian people eating soy protein but no evidence of an effect from soy foods as a whole (modest evidence)
• Moderately lower risk of breast cancer among people eating mushrooms (good evidence)
• Lower risk of breast cancer among postmenopausal women eating foods high in lignans—flaxseed and sesame, but also whole grains, berries and some other fruits, vegetables such as broccoli and kale, and green tea—or fiber (good evidence)
• Lower risk of breast cancer among people eating the highest levels of olive oil (good evidence)
• Moderately lower risk of breast cancer among people eating mushrooms (good evidence)
• Lower risk of breast cancer among postmenopausal women eating foods high in lignans—flaxseed and sesame, but also whole grains, berries and some other fruits, vegetables such as broccoli and kale, and green tea—or fiber (good evidence)
• Slightly higher risk of breast cancer among people eating red or processed meat, and increasing risk with higher consumption (good evidence)
• Little evidence of any impact for most breast cancer types among women eating higher levels of fat, dairy foods or calcium, but an increased risk of ER-negative tumors with higher levels of yogurt (good evidence)
• Higher risk of breast cancer among people eating higher levels of ultra-processed foods such as pastries, sweet or salty snacks, breakfast cereal, sweetened drinks, sweetened yogurt, hot dogs or meat nuggets, sausages, and other highly processed foods (good evidence)
• Slightly higher risk of breast cancer among people eating 5 or more eggs per week (modest evidence)

Risk of cancer as a whole:

• Lower risk of cancer among people eating fermented dairy foods (yogurt, kefir, cultured cheese)
• Lower cancer risk among people following anti-inflammatory diets compared to pro-inflammatory diets (good evidence)
• Lower risk of cancer as a whole among people eating the highest levels of olive oil (good evidence)
• Moderately lower risk of cancer as a whole among people eating mushrooms (modest evidence)
• Higher risk of cancer as a whole among people drinking higher levels of sugar-sweetened beverages (modest evidence)
• Higher risk of cancer as a whole among people eating higher levels of ultra-processed foods such as pastries, sweet or salty snacks, breakfast cereal, sweetened drinks, sweetened yogurt, hot dogs or meat nuggets, sausages, and other highly processed foods (good evidence)

Cancer mortality among people without cancer at the start of a study:

• Lower cancer mortality among people regularly eating chili peppers (strong evidence)
• Lower cancer mortality among people following a diet high in vegetables—but not starchy vegetables—and fruits before diagnosis (good evidence)
• Lower cancer mortality among people drinking several cups of coffee per day (good evidence)
• Higher cancer mortality among people eating higher levels of saturated fats (good evidence)

Moving More: strong to good evidence

Breast cancer mortality among people without cancer at the start of a study:

• Lower breast cancer mortality among people without cancer at baseline participating in higher levels of physical activity (good evidence)

Risk of cancer as a whole:

• A lower risk of a cancer diagnosis among people with higher levels of physical activity (strong evidence)

Cancer mortality among people without cancer at the start of a study:

• Lower cancer mortality among people without cancer at baseline and who had the highest levels of physical activity (strong evidence)

Recommended in at least one clinical practice guideline; see guidelines below

Combining Eating Well and Moving More: modest evidence

Breast cancer risk:

• Better balances of breast cancer-related sex hormones among people combining diet and exercise (modest evidence)

Managing Stress: strong to weak evidence

• Slightly higher cancer mortality among people without cancer at baseline with sleep durations of 6 hours or less (preliminary (conflicting) evidence)
• No evidence of higher cancer mortality among people with insomnia symptoms or who take daytime naps in combined analyses of studies

Creating a Healing Environment: mixed evidence

• Higher risk of female breast cancer among people exposed to x-rays or ionizing radiation from other medical imaging (strong evidence)
• Higher risk of breast cancer among people living in areas with higher air pollution levels (good evidence)
• Lower risk of breast cancer among people getting sun exposure (modest evidence)
• Substantially higher risk of breast cancer among people exposed to some pesticides (modest evidence)
• Higher risk of breast cancer among people with occupational exposures to PAHs (modest evidence)
• Slightly increased risk of breast cancer among people using permanent hair dye 
• Higher risk of breast cancer among women with higher body levels of heavy metals (preliminary evidence)
• Higher risk of breast cancer among women with higher body levels of phthalates or PCBs (preliminary evidence)
• Slightly higher risk of breast cancer among people applying semi-permanent dye to others non-professionally (preliminary evidence)
• Higher risk of breast cancer among women with a sister with breast cancer and using hair straightener or applying it to others non-professionally (weak evidence)
• Insufficient (conflicting) evidence of any higher risk of breast cancer among people working at night

Risk of cancer as a whole:

• Higher risk of cancer as a whole among people exposed to dioxin (TCDD) (strong evidence)
• Higher risk of cancer, including secondary cancer, among people receiving radiation therapy  (strong evidence)
• Higher risk of cancer as a whole among people exposed to wood dust (strong evidence)
• Slightly higher risk of solid cancers among adults exposed to low cumulative doses  of ionizing radiation (modest evidence)
• Slightly higher risk of cancer as a whole among people living in urban areas characterized by higher concentrations of polycyclic aromatic hydrocarbons (PAHs) (modest evidence)
• Higher risk of childhood cancer among children exposed to PAHs from playgrounds surfaced with poured rubber (preliminary evidence)
• Slightly lower risk of cancer and cancer-related death as a whole among people ever using hair dye (weak evidence)
• Insufficient (conflicting) evidence of lower risk of cancer among adults eating organic foods 
• No evidence of an effect on risk of solid cancers other than melanoma and other skin cancer among people using indoor tanning devices

Cancer mortality among people without cancer at the start of a study:

• Slightly higher risk of cancer mortality among people without cancer at baseline working at night (good evidence)
• Small increases in mortality from cancer as a whole among people without cancer at baseline with higher exposures to particulate air pollutants(modest evidence)

Sharing Love and Support: mixed evidence

Risk of cancer as a whole:

• Higher risk of cancer and cancer mortality among people with lower levels of social support, with some differences between men and women and between white and black Americans (good evidence)

Manage your body weight: good and modest evidence

Manage depression: good evidence

Manage high blood sugar and insulin resistance: good and modest evidence

Risk of cancer as a whole:

• Higher risk of invasive cancer as a whole among postmenopausal women with diabetes (modest evidence)

Cancer mortality among people without cancer at the start of a study:

• Higher cancer-specific mortality among people without cancer at baseline with poorer markers of blood sugar balance and insulin sensitivity (good evidence)

Limit alcohol: good evidence

Breast cancer risk:

• Moderately higher risk of breast cancer among people drinking 35 grams of alcohol per day—about 2 glasses of wine, 2 bottles of beer or 4 ounces of liquor—with increasing risk with even higher amounts (good evidence)

We have not yet published our Limit Alcohol handbook; this statement is from our research so far.

Don’t smoke: strong and modest evidence

Breast cancer risk:

• 14% higher risk of breast cancer among women who had ever smoked, increasing to 24% higher risk among women who started smoking before age 17 and 35% higher risk among women with a family history of breast cancer (modest evidence)

Cancer as a whole:

• A clear link between tobacco use and risk of cancer as a whole (good evidence)

We have not yet published our Don’t Smoke handbook; this statement is from our research so far. 

Breastfeeding

Breastfeeding brings many benefits to the mother as well as the infant, including reducing the mother’s risk of breast cancer.¹⁶National Cancer Institute. Reproductive History and Cancer Risk. National Institutes of Health. November 9, 2016. Viewed October 5, 2018. Many organizations, including the University of Texas MD Anderson Cancer Center, recommend breastfeeding your infant for at least six months, and longer is better.¹⁷Cordeiro B. Breastfeeding lowers your breast cancer risk. The University of Texas MD Anderson Cancer Center. Viewed October 5, 2018.

Green tea or EGCG: modest evidence

Cancer as a whole:

• Insufficient (conflicting) evidence of an effect on risk of cancer as a whole among people drinking green tea, although some evidence shows lower risk of cancer mortality among women but not men

Mediterranean diet: good evidence

Metformin: mixed evidence

• Fewer grade 3 tumors or triple negative tumors, but higher incidence of ER or PR positive tumors, among people with breast cancer (not specific to diabetes) using metformin at the time of diagnosis (preliminary evidence)
• Lower Breast Imaging Reporting and Data System (BIRADS) scores and positive pathological biopsy rate among overweight/obese premenopausal women without diabetes treated with metformin (preliminary evidence)

Breast cancer mortality among people without cancer at the start of a study:

• Lower breast cancer-specific mortality among people without cancer at baseline with diabetes treated with metformin (modest evidence)
• Slightly lower risk of breast cancer and lower breast cancer-specific mortality among people without cancer at baseline (not specific to diabetes) treated with metformin (modest evidence)

Risk of cancer as a whole:

• Lower risk of cancer as a whole among people with diabetes treated with metformin (modest evidence)

Cancer mortality among people without cancer at the start of a study:

• No evidence of an effect on cancer-specific mortality among people at high risk of type 2 diabetes treated with metformin in a very large study

Time in nature: modest evidence

Cancer as a whole:

• No evidence of an effect on risk of cancer as a whole among people treated with oral vitamin C in large controlled studies
• A link between low vitamin C levels and risk of cancer as a whole (modest evidence)

Vitamin D: strong to weak evidence

Risk of cancer as a whole:

• Lower risk of cancer among healthy adults aged 70 years or older taking vitamin D supplements (modest evidence)
• Lower risk of cancer among people with higher 25(OH)D levels (weak evidence)

Cancer mortality among people without cancer at the start of a study:

• Slightly lower cancer mortality among people without cancer at baseline taking vitamin D supplements (strong evidence)
• Lower cancer mortality among people without cancer at baseline with higher 25(OH)D levels (good evidence)

Vitamin D and calcium together: mixed evidence

See Vitamin D › for the evidence

Breast cancer risk: 

• No evidence of an effect on risk of invasive breast cancer among postmenopausal women treated with calcium plus vitamin D
• See also an increase in breast cancer risk among women with higher baseline intake of vitamin D in Safety and precautions ›

Risk of cancer as a whole:

• Lower risk of cancer as a whole among postmenopausal women treated with vitamin D and calcium (good evidence)

Preliminary or weak evidence for reducing cancer risk

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) means the practice or therapy may be linked to the outcomes described, although substantial uncertainty remains. 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) may mean that the effects are small or that a high degree of uncertainty remains about the links between the practice or therapy and the outcomes described.

Further therapies that may reduce risk of breast cancer

These therapies are reported to reduce risk of breast cancer. We have not fully assessed the evidence, although we provide preliminary reviews as linked.

Screening for cancer in dense breasts

Breast density indicates a higher proportion of fibrous and glandular tissue compared to fatty tissue. Women with dense breasts have a higher risk of breast cancer. The denser the breasts, the higher the risk. Dense tissue can also make tumors more difficult to find in a mammogram, leading to more “missed” cancers during screening.¹⁸About Dense Breasts. Centers for Disease Control and Prevention. Viewed May 18, 2024.

A large study in the Netherlands found that supplementing mammograms with magnetic resonance imaging (MRI) for women with very dense breast tissue reduced missed cancers (interval cancers) more than mammography alone.¹⁹Bakker MF, de Lange SV et al. Supplemental MRI screening for women with extremely dense breast tissue. New England Journal of Medicine. 2019 Nov 28;381(22):2091-2102.

Helpful links related to dense breasts

How integrative experts approach cancer risk

Clinical practice guidelines

Physical activity is beneficial for the prevention of several types of cancer including breast cancer.

Breast Cancer: Medication Use to Reduce Risk ›

In their 2019 guideline, the USPSTF recommends that clinicians offer to prescribe risk-reducing medications, such as tamoxifen, raloxifene, or aromatase inhibitors, to women aged 35 or older who are at increased risk for breast cancer and at low risk for adverse medication effects, but do not routinely use risk-reducing medications among women without increased risk of breast cancer

Vitamin, Mineral, and Multivitamin Supplementation to Prevent Cardiovascular Disease and CancerUS Preventive Services Task Force Recommendation Statement ›

Recommends against the use of beta carotene or vitamin E supplements for the prevention of cardiovascular disease or cancer

The current evidence is insufficient to assess the balance of benefits and harms of the use of single- or paired-nutrient supplements (other than beta carotene and vitamin E) for the prevention of cardiovascular disease or cancer. 

Published programs and approaches

Lise Alschuler, ND, FABNO, and Karolyn Gazella

Lorenzo Cohen, PhD, and Alison Jefferies, MEd

Other expert assessments

Recommended actions:

Actions the CDC recommends for reducing risk of breast cancer:

Commentary

CancerChoices advisor Ted Schettler, MD, MPH: It takes a village (or a whole country) to reduce the risk of breast cancer

Reducing risk factors for breast cancer “cannot be accomplished by individuals alone. Public health strategies to re-shape the terrain are essential.”²⁰Schettler T. The Ecology of Breast Cancer: The Promise of Prevention and the Hope for Healing. Science and Environmental Health Network and The Collaborative on Health and the Environment. October 2013. Many of these can only partially be addressed by changes in individual behavior. Multi-level public-health and policy interventions at the population level are also necessary in order to re-design system conditions in more favorable ways.

Dr. Schettler synthesizes the research to 2013 and presents practical measures for individuals, healthcare professionals, public health officials, community planners, businesses, schools, governments and farmers to help reduce the burden of this disease at all levels.

Discussing public-health strategies is beyond the scope of this commentary, but we refer readers to Dr. Schettler’s book and to the work of organizations such as the Science and Environmental Health Network › and the Collaborative on Health and the Environment ›

Helpful links

Keep reading about breast cancer

Choose what to read next

• Introduction
• At any time during your breast cancer experience
• Preparing for breast cancer treatment
• During breast cancer treatment
• Surviving and thriving with and beyond breast cancer
• Reducing your risk of breast cancer
• Are you a health professional?

Authors

Laura Pole, MSN, RN, OCNS

Senior Clinical Consultant

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Laura Pole is senior clinical consultant for CancerChoices. Laura is an oncology clinical nurse specialist who has been providing integrative oncology clinical care, navigation, consultation, and education services for over 40 years. She is the co-creator and co-coordinator of the Integrative Oncology Navigation Training at Smith Center for Healing and the Arts in Washington, DC. Laura also manages the “Media Watch Cancer News That You Can Use” listserv for Smith Center/Commonweal. In her role as a palliative care educator and consultant, Laura has served as statewide Respecting Choices Faculty for the Virginia POST (Physician Orders for Scope of Treatment) Collaborative as well as provided statewide professional education on palliative and end-of-life care for the Virginia Association for Hospices and Palliative Care.

For CancerChoices, Laura curates content and research, networks with clinical and organizational partners, brings awareness and education of integrative oncology at professional and patient conferences and programs, and translates research into information relevant to the patient experience as well as clinical practice.

Laura sees her work with CancerChoices as a perfect alignment of all her passions, knowledge and skills in integrative oncology care. She is honored to serve you.

Laura Pole, MSN, RN, OCNS Senior Clinical Consultant

Nancy Hepp, MS

Lead Researcher

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Ms. Hepp is a researcher and communicator who has been writing and editing educational content on varied health topics for more than 20 years. She serves as lead researcher and writer for CancerChoices and also served as the first program manager. Her graduate work in research and cognitive psychology, her master’s degree in instructional design, and her certificate in web design have all guided her in writing and presenting information for a wide variety of audiences and uses. Nancy’s service as faculty development coordinator in the Department of Family Medicine at Wright State University also provided experience in medical research, plus insights into medical education and medical care from the professional’s perspective.

Nancy Hepp, MS Lead Researcher

Gwendolyn Stritter, MD

Physician and CancerChoices advisor

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Dr. Stritter is board-certified in anesthesiology. She was also certified in pain medicine from 1996 to 2016 and served as the director of the Kaiser San Jose Pain Medicine Clinic for 10 years. Wishing to pursue a more patient-centered style of practice, Gwen subsequently trained with Dr. Mark Renneker, honing her medical advocacy skills to help those with life-threatening health problems. Her own high risk for breast cancer led her to focus on that area in particular.

During her 13 years of clinical advocacy practice, she appeared on radio, lectured and wrote many articles on medical advocacy. She also coauthored the chapter on clinical advocacy in the textbook Patient Advocacy for Healthcare Quality: Strategies for Achieving Patient-Centered Care (2007).

As fate would have it, Dr. Stritter was diagnosed with breast cancer in 2013. Although side effects of treatment forced closure of her medical advocacy practice, she continues to enjoy attending several breast cancer conferences every year, learning best integrative oncology practices and mentoring the next generation of breast cancer medical advocates.

Gwendolyn Stritter, MD Physician and CancerChoices advisor

Reviewers

Michael Lerner

Co-Founder

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Michael Lerner is co-founder of Commonweal and co-founder of the Commonweal Cancer Help Program, Healing Circles, The New School at Commonweal, and CancerChoices. He has led more than 200 Commonweal Cancer Help Program retreats to date. His book Choices In Healing: Integrating the Best of Conventional and Complementary Approaches to Cancer was the first book on integrative cancer care to be well received by prominent medical journals as well as by the patient and integrative cancer care community.

Michael Lerner Co-Founder

Walter Tsang, MD

Integrative oncologist

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Dr. Walter Tsang is quadruple board-certified in medical oncology, hematology, lifestyle medicine, and internal medicine. In addition to providing cutting-edge treatments for cancer and blood diseases, Dr. Tsang regularly advises his patients on nutrition, physical activity, stress management, and complementary healing methods. He has seen firsthand how this whole-person approach improved his patients’ quality of life and survival.

Outside of his clinical practice, Dr. Tsang teaches integrative oncology at the UCLA Center for East-West Medicine and directs an educational seminar program for cancer survivors in the community. His research interests focus on comparing and integrating the traditional Eastern and modern Western perspectives of cancer care. His fluency in Chinese further allows him to study the enormous integrative medicine literature published in the East that is not easily accessible to the West due to the language barrier.

Dr. Tsang is an active member of the American Society of Clinical Oncology, Society for Integrative Oncology, and American College of Lifestyle Medicine. He currently practices in the Inland Empire region of Southern California.

Walter Tsang, MD Integrative oncologist

Last update: October 16, 2024

Last full literature search: January 2023

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.

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