Incidence of intraductal carcinoma, multifocality and bilateral significant disease in radical prostatectomy specimens from Japan and United States

Significant differences, including epidemiologic, clinical, pathologic and genetic, exist between Asian and Caucasian prostate cancer. Detailed pathologic data are, however, scarce. We studied in detail and compared the pathological features of prostate cancer in radical prostatectomy specimens in 228 patients (117 Japan, 111 US). Japanese prostate cancer had a higher Gleason grade group (mean 2.67 vs. 2.42 US, P < 0.05), but lower pathological stage (72 % pT2 and 28 % pT3 vs 55% pT2 and 45% pT3 US, P < 0.05). Japanese cancer showed significantly more tumor foci (3.8 vs 2.9 US, P < 0.05), and higher incidence of bilateral significant disease (81.3 % vs. 66.7 % US, P < 0.05). The dominant tumor nodules in Japanese cases had higher Gleason grade group (mean 2.73 vs. 2.40 US, P < 0.05). The incidence of intraductal carcinoma was significantly higher in Japanese patients (35.3 % vs. 12.6 % US, P < 0.01), which was independent of Gleason score (7: 30.9 % Japan vs 11.8 % US, P < 0.01; >= 8: 87.5 % Japan vs 28.6 % US, P < 0.01) and tumor stage (pT2: 24.1 % Japan vs 6.6 % US, P < 0.01; pT3: 62.9 % Japan vs 20 % US, P < 0.01). These findings demonstrate distinct pathological features in prostate cancer between Japanese and Caucasian patients, and may have important diagnostic and therapeutic implications.