Twenty-seven studies (15 cohort and 12 case-control studies) were included in the review (1,893,571 male participants). All cohort studies scored 8 in Newcastle Ottawa scale and with case-control studies the total score was 7.7. Follow-up ranged from two years to 17 years.
The meta-analysis showed that use of statins significantly reduced the risk of both total prostate cancer (RR 0.93, 95% CI 0.87 to 0.99; Ι²=82%; 26 studies) and advanced prostate cancer (RR 0.80, 95% CI 0.70–0.90; Ι²=38%; seven studies). Also the results showed that long term use of statin (five years and more) did not significantly affect the risk of total prostate cancer.
Subgroup analyses showed no significant difference between different study designs and whether or not studies were adjusted for prostate specific antigen testing; however, there was a significant association of statin use and reduced risk of prostate cancer for the studies adjusted for BMI and/or adverse life style and the studies published after Bonovas et al. Sensitivity analysis confirmed the stability of results. Cumulative meta-analysis showed a change in trend of reporting risk from positive to negative in statin users between 1993 and 2011.