Recent studies have suggested that metformin, a commonly used medication for diabetes, may have a positive impact on reducing the risk of prostate cancer. However, the findings from previous research have been inconsistent, leading to a need for further investigation. A new meta-analysis aimed to evaluate the effects of metformin on the clinical outcomes of prostate cancer patients, including the incidence, recurrence, and mortality rates.

The study involved a systematic review of data from 10 electronic databases and 4 registries to analyze the relationship between metformin use and prostate cancer risk. The results revealed that individuals who used metformin had a lower incidence of prostate cancer compared to those who did not use the medication. The risk reduction was statistically significant, with a relative risk (RR) of 0.82 and a 95% confidence interval (CI) of 0.74–0.91.

Furthermore, the analysis also explored the impact of metformin on prostate cancer recurrence and mortality rates. While metformin use was associated with a reduced risk of cancer recurrence, the results were not statistically significant, with an RR of 0.97 and a 95% CI of 0.81–1.15. Additionally, metformin use was not found to be linked to prostate cancer mortality, with an RR of 0.94 and a 95% CI of 0.81–1.09.

Subgroup analyses revealed that the type of study (cohort study) and the geographic population (Asia and Europe) influenced the effectiveness of metformin in reducing prostate cancer incidence. Moreover, a positive linear correlation was observed between the duration of metformin use and its protective effects against prostate cancer.

In conclusion, the meta-analysis demonstrated a significant association between metformin use and a decreased incidence of prostate cancer. However, metformin did not show a clear impact on cancer recurrence or mortality rates. The study also highlighted the importance of considering the duration of metformin use in relation to its effectiveness in reducing prostate cancer risk.