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

Histopathological comparison of clinical prostatic adenocarcinoma between Japan and the United States (US) has been made with retrospective analyses on 1,037 and 987 cases, respectively. All cases were histologically evaluated by the same pathologist (M.H.) without previous knowledge of clinical information according to application of the Japanese General Rules for Prostatic Cancer (JGRPC) based on the predominant degree of histological differentiation, the nuclear grading by WHO classification and the Gleason grading systems. The age distribution of the patients was slightly different among both groups. However, this difference appeared not to be essential, because there existed difference of the date on diagnosis between two groups. Even though considering this time difference on registration, much more cases from Japan had stage D disease. The observed incidence of the histological differentiation classified by JGRPC among over-all cases did not show significant difference, however, the incidence among the cases with same stage between two groups differed with some statistical significance. Much more cases from the US fell in well differentiated adenocarcinoma and frequency of moderately differentiated adenocarcinoma was higher in the Japanese even in the cases diagnosed at advanced stages. The observed incidence of nuclear grade 3 was also higher in the Japanese. Gleason primary and secondary grade 5 and score 9-10 appeared more frequently in the cases from Japan.(ABSTRACT TRUNCATED AT 250 WORDS)