Metformin is a common medicine used to treat Type II diabetes. It is an “insulin sensitizer” that affects cellular metabolism. Some research suggests that metformin may also have “antineoplastic” (i.e., anti-cancer) effects on some cancer cells.
Recently, researchers have started to investigate the potential for metformin to improve survival for men with prostate cancer. A new study by researchers in Wisconsin looked at the survival-related effects of combining metformin with ADT for patients with advanced prostate cancer. This was a retrospective, observational study that used data from United States National Veterans Affairs databases. The medication history and health-related information for 87,344 prostate cancer patients on ADT was analyzed in order to search for associations between metformin use and survival. The sample was divided into three groups: 1) men on ADT without diabetes, who did not take metformin (61%); 2) men on ADT with diabetes, who did not take metformin (22%); 3) men on ADT with diabetes, who also took metformin for at least 180 days (17%).
· Metformin use was associated with improved overall survival and improved cancer-specific survival. Men with diabetes who were on ADT and metformin demonstrated improved survival outcomes compared to diabetic men who were on ADT only.
· Metformin use was associated with reduced risk of skeletal-related events, which the researchers used as an indicator of disease progression.
· The duration of time over which men received treatment with metformin may have impacted survival outcomes, as well. The researchers suggest that beneficial effects associated with metformin may increase over time.
These findings suggest a potentially additive effect of ADT and metformin. The study authors hypothesized that metformin may exploit the ‘metabolic abnormalities’ of prostate cancer cells that are initially induced by ADT. Metformin may therefore tip these cells ‘over the edge’ and lead them to undergo apoptosis, or cell death. Additional, prospective studies are needed to investigate the potential for metformin to improve survival outcomes when used in combination with ADT.
To read the full article, please see:
Richards, K. A., Liou, J. I., Cryns, V. L., Downs, T. M., Abel, E. J., & Jarrard, D. F. (2018). Metformin use is associated with improved survival for patients with advanced prostate cancer on androgen deprivation therapy. The Journal of Urology, 200(6), 1256-1263. doi: 10.1016/j.juro.2018.06.031