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.”[i] 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.[ii]
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.”[iii]
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.”[iv]
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] 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
[ii] Sayyid R, Flesher N. “Potential role for metformin in urologic oncology.” Investig Clin Urol. 2016 May; 57(3): 157–164.
[iii] 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.