[Histopathological comparison of stage A prostatic adenocarcinoma in Japan and the United States].

Histopathological characteristics of stage A prostatic adenocarcinoma from Japan (137 cases) and the United States (51 cases) were comparatively evaluated by retrospective analysis. All cases were examined by one referee pathologist (MH) using classification based on Japanese General Rules for Prostatic Cancer (JGRPC), nuclear grading by Mostofi-WHO system and Gleason grading. The incidences of the cases with well differentiated, low nuclear anaplasia and Gleason grade 1 or 2 on primary and secondary grades as well as histologic score 2-4 were much more higher in the cases from Japan as compared with those from the US. In the cases from the US proportion of the cases with moderately differentiated adenocarcinoma and grade 2 nuclear anaplasia exceeded those with well differentiated and grade 1 anaplasia. Adenocarcinomas with Gleason grade 3 in primary and secondary grade and 6-8 of histologic score were also more frequently observed in the cases from the US. No different distribution of each histologic grade could be obtained among the Japanese cases classified stage A2 and entire cases from the US. These results suggest that much more stage A adenocarcinoma in the US might fall into A2 if strict criteria was applied for subcalssification of stage A, which may reflected in the remarkable difference in the incidence of clinical prostatic carcinoma.