Substantial geographical differences in prostate cancer (PCa) incidence and mortality exist, being lower among Asian (ASI) men compared with Caucasian (CAU) men. We prospectively compared PCa prevalence in CAU and ASI men from specific populations with low penetrance of prostate-specific antigen screening.

Prostate glands were prospectively obtained during autopsy from men who died from causes other than PCa in Moscow, Russia (CAU), and Tokyo, Japan (ASI). Prostates were removed en-block and analyzed in toto. We compared across the 2 populations PCa prevalence, number and Gleason score (GS) of tumour foci, pathological stage, spatial location, and tumor volume using χ², Mann–Whitney–Wilcoxon tests, and multiple logistic regression. All statistical tests were two-sided.

Three hundred twenty prostates were collected, 220 from CAU men and 100 from ASI mean. The mean age was 62.5 in CAU men and 68.5 years in ASI men (P < .001). PCa prevalences of 37.3% in CAU men and 35.0% in ASI men were observed (P = .70). Average tumor volume was 0.303cm³. In men aged greater than 60 years, PCa was observed in more than 40% of prostates, reaching nearly 60% in men aged greater than 80 years. GS 7 or greater cancers accounted for 23.1% and 51.4% of all PCa in CAU and ASI men, respectively, (P = .003). When adjusted for age and prostate weight, ASI men still had a greater probability of having GS 7 or greater PCa (P = .03).

PCa is found on autopsy in a similar proportion of Russian and Japanese men. More than 50% of cancers in ASI and nearly 25% of cancers in CAU men have a GS of 7 or greater. Our results suggest that the definition of clinically insignificant PCa might be worth re-examining.