Correlation between metformin intake and prostate cancer

Background: The relationship between metformin intake and prostate cancer incidence remains unclear. Therefore, we examined the correlation between prostate cancer and metformin use.Methods: The subjects were diabetes patients aged ≥50 years who had been diagnosed with prostate cancer and had undergone surgery at Seoul St. Mary's Hospital. Groups taking metformin (MET(+) group) and not taking metformin (MET(–) group) were divided and compared.Results: The mean preoperative prostate-specific antigen (PSA) levels in the MET(–) and MET(+) groups were 10.7±11.9 and 8.0±5.6 ng/mL, respectively, with no statistically significant difference between the two groups (P=0.387). The average prostate volume of the MET(–) group was 82.4±98.0 mL, and the average prostate volume of the MET(+) group was 55.4±20.1 mL, but there was no statistically significant difference between the two groups (P=0.226). The mean PSA velocity also did not show a significant difference between the two groups (0.025±0.102 ng/mL vs. 0.005±0.012 ng/mL, P=0.221).Conclusions: We did not identify a significant positive correlation between metformin and prostate cancer. However, preoperational PSA and PSA velocity tended to be lower in the MET(+) group. A sophisticated prospective study with a large sample size should be planned.