Researchers conducted a review of 26 studies to determine the possible effects of metformin and ethnicity on the risk of prostate cancer.
Jeffrey Johnson and his team in Alberta, Canada recently published a systematic review in BMC Cancer analyzing the association between metformin, ethnicity, and the risk of prostate cancer. They searched several databases and chose 26 studies for the review. There were 23 studies with a Western-based population (Europe and North America) and three studies with an Asian based population (mainly participants from Taiwan). There were 1,171,643 Western-based participants and 400,664 Asian based participants included in the review. The results did not show a significant decrease in the risk of prostate cancer in either the Western- or the Asian based groups.
Data shows that type 2 diabetes carries an increased risk in the development of some cancers. Diabetes and cancer share some similarities in pathophysiology. Insulin resistance occurs when the body is unable to properly use the insulin produced by the pancreas. This causes the pancreas to increase production, leading to hyperinsulinemia (excess insulin in the blood). Hyperinsulinemia is hypothesized to increase the risk of developing certain cancers.
Metformin is a common medication used in the management of type 2 diabetes. There is significant interest in its potential benefits in cancer risk reduction and treatment. Ethnicity might play a role in the effect of metformin on cancer management, with some studies indicating that the risk of prostate cancer may be reduced only in Asian participants.
The review was limited by the absence of individual data for each participant. This is an issue because the studies were classified based on the origin of the database, but the studies potentially included people of different ethnicities. The studies selected for the review had varying definitions for metformin exposure. While some studies defined exposure as presence or absence of metformin in the participant’s medication regimen, other studies made a comparison with another medication or diet. While this review indicates there is likely no correlation between metformin and the risk of developing prostate cancer, the limitations noted above suggest more research is required in this area.
Written by Anuolu Bank-Oni, Pharm.D, CDE, BCGP
Reference: Chen, C.B et al. Metformin, Asian ethnicity and risk of prostate cancer in type 2 diabetes: a systematic review and meta-analysis. BMC Cancer (2018) 18:65 DOI 10.1186/s12885-017-3934-9
