Metformin, a prescription drug used to manage diabetes, has shown some benefits in lower risks of cancer and better survival, mostly among people with diabetes or high blood sugar.

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This section does not replicate the other information on this topic but provides additional details or context most relevant to professionals.

Patient education handout and poster

A printable two-page patient education handout explains what research indicates about when metformin may be helpful in cancer care.

Is Using Metformin for Cancer Helpful and Safe? ›

At the 2024 congress of the Oncology Nursing Society, we presented a poster on what research indicates about when metformin may be helpful in cancer care.

Open the full poster ›

Open the poster content, including additional tables ›

Use in telemedicine

Metformin was found appropriate for prescription via telemedicine among people with prostate cancer in a small RCT.1Galsky MD, Shahin M et al. Telemedicine-enabled clinical trial of metformin in patients with prostate cancer. JCO Clinical Cancer Informatics. 2017 Nov;1:1-10. 

Modes of action: metabolic factors

An article published in 2021 discusses metformin’s effects on cell signaling pathways, metabolism, growth, proliferation, inflammation, tumorigenesis and senescence. Metformin modulates immune response, autophagy, mitophagy, endoplasmic reticulum stress and apoptosis, and exerts epigenetic effects. It protects against oxidative stress and genomic instability, preserves telomere length, and prevents stem cell exhaustion.2Ala M, Ala M. Metformin for cardiovascular protection, inflammatory bowel disease, osteoporosis, periodontitis, polycystic ovarian syndrome, neurodegeneration, cancer, inflammation and senescence: What is next? ACS Pharmacology and Translational Science. 2021 Nov 1;4(6):1747-1770.

Metformin asserts indirect effects on the tumor microenvironment, such as lowering inflammation and blood glucose.3Coyle C, Cafferty FH, Vale C, Langley RE. Metformin as an adjuvant treatment for cancer: a systematic review and meta-analysis. Annals of Oncology. 2016;27(12):2184-2195; Li D, Yeung S-CJ, Hassan MM, Konopleva M, Abbruzzese JL. Anti-diabetic therapies affect risk of pancreatic cancer. Gastroenterology. 2009;137(2):482-488; Kasznicki J, Sliwinska A, Drzewoski J. Metformin in cancer prevention and therapy. Annals of Translational Medicine. 2014;2(6):57. It also reduces the amount of circulating estrogen and testosterone, both of which can stimulate the growth of hormone-dependent tumors such as breast cancer and prostate cancer.4Lawenda, BD. Metformin supplementation and cancer treatment. Integrative Oncology Essentials. February 19, 2013. Viewed August 11, 2022.

Metformin accumulates in colonic tissues, which may contribute to the reduced risk of colorectal cancer associated with metformin use.5Paleari L, Burhenne J et al. High accumulation of metformin in colonic tissue of subjects with diabetes or the metabolic syndrome. Gastroenterology. 2018 Apr;154(5):1543-1545.

Notable preclinical evidence

Notable preclinical evidence is presented here; clinical evidence is summarized in How can metformin help you? What the research says ›

Treatment response

Cancer as a whole

Breast cancer

  • Downregulated a series of pro-tumorigenic micro-RNAs following metformin treatment in breast cancer cells10Zhou Y, Zhang X, Gu C, Xia J. Diabetes mellitus is associated with breast cancer: systematic review, meta-analysis, and in silico reproduction. Panminerva Medica. 2015 Sep;57(3):101-8.
  • Resensitized breast cancer cell lines to doxorubicin, either alone or in combination with tamoxifen, and reversed multidrug resistance11Davies G, Lobanova L et al. Metformin inhibits the development, and promotes the resensitization, of treatment-resistant breast cancer. PLoS One. 2017 Dec 6;12(12):e0187191.

Colorectal cancer

Endometrial cancer


  • Inhibited tumor cell metabolism and increased T-cell activation in melanoma cell studies; induced regressions and tumor clearance in mice14Scharping NE, Menk AV, Whetstone RD, Zeng X, Delgoffe GM. Efficacy of PD-1 blockade is potentiated by metformin-induced reduction of tumor hypoxia. Cancer Immunology Research. 2017 Jan;5(1):9-16.

Managing side effects: cognitive impairment

  • Prevented cognitive impairment due to cisplatin via treatment with metformin prior to cisplatin treatment15Zhou W, Kavelaars A, Heijnen CJ. Metformin prevents cisplatin-induced cognitive impairment and brain damage in mice. PLoS ONE. 2016;11(3):e0151890.

Helpful links for professionals

Cejuela M, Martin-Castillo B, Menendez JA, Pernas S. Metformin and breast cancer: Where are we now? International Journal of Molecular Sciences. 2022 Feb 28;23(5):2705.

Kamarudin MNA, Sarker MMR, Zhou JR, Parhar I. Metformin in colorectal cancer: molecular mechanism, preclinical and clinical aspects. Journal of Experimental and Clinical Cancer Research. 2019 Dec 12;38(1):491.

Barczyński B, Frąszczak K, Kotarski J. Perspectives of metformin use in endometrial cancer and other gynaecological malignancies. Journal of Drug Targeting. 2022 Apr;30(4):359-367.

Cancer Strategies Journal: Clinical Pearls, Summer 2013 ›
See “Off-label use of metformin”

Keep reading about metformin


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

Andrew Jackson, ND

Research Associate
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Andrew Jackson, ND, serves as a CancerChoices research associate. As a naturopathic physician practicing in Kirkland, Washington, he teaches critical evaluation of the medical literture at Bastyr University in Kenmore, Washington. His great appreciation of scientific inquiry and the scientific process has led him to view research with a critical eye.

Andrew Jackson, ND Research Associate


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

Dr. Fuller-Shavel is a GMC-registered integrative medicine doctor with degrees in medicine and natural sciences from the University of Cambridge. Dr. Fuller-Shavel is a fellow of the College of Medicine and the vice chair for BSIO (British Society for Integrative Oncology). Alongside her science and medical training, Dr. Fuller-Shavel holds multiple qualifications in nutrition, integrative medicine, health coaching, herbal medicine, yoga, mindfulness and other mind-body approaches.

Dr. Fuller-Shavel is the director of Synthesis Clinic, an award-winning multidisciplinary integrative medicine practice in Hampshire, UK, specializing in women’s health, gut health (microbiome and gut-brain axis) and mental health. She combines her clinical work in women’s health and supporting patients with breast and gynecological cancer with education and training for healthcare professionals and research in precision cancer medicine and precision nutrition.

Nina Fuller-Shavel, MB, BChir, MA Hons, FBANT, IFMCP, DipIM, PG Cert RYT300

Last update: April 28, 2024

Last full literature review: March 2022

CancerChoices provides information about integrativein 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 psychosocialtherapy, and acupuncture therapies and self carelifestyle 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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