Originally published 12/1/2017
Metformin, a drug increasingly used to manage high blood sugar in diabetes, is proving to be beneficial and versatile, especially when used in conjunction with healthy diet and exercise. As succinctly stated on WebMD, controlling high blood sugar helps prevent kidney damage, blindness, nerve problems, loss of limbs and sexual function problems. In the blog below, which we posted over three years ago, we explained that metformin also appears to have antitumor effects against endocrine-related cancers such as breast, prostate, ovarian and others.
A July, 2021 published research paper affirms this: “Metformin seems to be a promising chemopreventive and adjuvant agent in cancer management, modulating tumor cell metabolism and microenvironment…Moreover, its combination with statins might represent a promising therapeutic strategy to tackle the progression of endocrine-related tumors.”[i] As in the original blog, the optimism of the authors is balanced with a caution that more studies are needed. Still, more than three years since then, all signs indicate that metformin research is moving in the right direction when it comes to hormonally fueled malignancies such as prostate cancer.
A drug called metformin may offer a breakthrough in literally preventing prostate cancer. The medication itself is “the most widely used drug to treat diabetes Type 2, and is one of only two oral antidiabetic drugs on the World Health Organization (WHO) list of essential medicines.”[ii] A review of published clinical literature by Sayyid & Fleshner, metformin appears to have one or more effects in the body that discourage the formation of cancerous tumors.[iii]
Numerous studies have shown that metformin disrupts androgen receptor functions in prostate cancer cells, thereby keeping tumors from growing. It also interferes with how cancer cells use glucose (sugar), something that cancer cells need for their survival and progression. There are other biochemical interactions as well, all of which point to metformin’s ability to prevent the action of prostate cancer at a very basic level.
Not only does metformin possess properties that deter prostate cancer from beginning, but for patients receiving treatment for prostate cancer, it may actually help make the treatment more effective. Some studies have shown that for patients taking metformin, recurrence rates are lower; patients undergoing radiation for their prostate cancer seem to respond better to the treatment; and there is a lower probability of metastatic disease. Notably, “A case-control study limited to patients with cancer at the Mayo Clinic found a statistically significant reduction of mortality in patients with prostate cancer on metformin.”[iv]
Researchers agree that it is too soon to start prescribing metformin purely as a preventative medication for prostate cancer. There is not sufficient evidence that it would be safe or effective for such use. On the other hand, “the future appears bright for metformin as either a monotherapy or an adjunct to androgen deprivation therapy, external-beam radiation therapy, prostatectomy, or chemotherapy.”[v]
This opens the door for work developing new prostate cancer therapies that incorporate the use of metformin, offering new hope for patients newly diagnosed with prostate cancer as well as those with recurrent or advanced disease.
[i] León-González AJ, Jiménez-Vacas JM, Fuentes-Fayos AC, Herrera-Martínez AD et al. Role of metformin and other metabolic drugs in the prevention and therapy of endocrine-related cancers. Curr Opin Pharmacol. 2021 Jul 23;60:17-26.
[ii] Dronsfield A, Ellis P. “Drug discovery: metformin and the control of diabetes.” Education in Chemistry. 2011 Nov;185-87. http://www.rsc.org/images/eic_nov2011_metformin_tcm18-210010.pdf
[iii] Sayyid R, Flesher N. “Potential role for metformin in urologic oncology.” Investig Clin Urol. 2016 May; 57(3): 157–164.
[iv] Hankinson SJ, Fam M, Patel NN. A review for clinicians: prostate cancer and the antineoplastic properties of metformin. Urol Oncol. 2017 Jan;35(1):21-29.