Prostate carcinoma detection and increased prostate‐specific antigen levels after 4 years in Dutch and Japanese males who had no evidence of disease at initial screening

Abstract

In the current study, the authors set out to investigate the possibility that increased prostate-specific antigen (PSA) levels in Dutch and Japanese men without suspicious findings at initial prostate cancer screening were indicative of the risk of newly developing clinical malignancy in the Netherlands and Japan. Between 1992 and 2000, 2650 men ages 55-74 years who had PSA levels < 4.0 ng/mL and no suspicious findings on digital rectal examination were entered into the current study from a population-based prostate cancer screening cohort in Gunma Prefecture, Japan. In addition, between 1994 and 1997, 3163 men with the same clinical background were entered into the current study from the Rotterdam (Netherlands) Section of the European Randomized Study of Screening for Prostate Cancer (ERSPC). Prostate carcinoma incidence and the cumulative probability of freedom from PSA increases to levels > 2.0, 3.0, and 4.0 ng/mL, respectively, after 4 years of observation were compared between the Japanese and Dutch populations. The predictive value of initial PSA level, age at study entry, and geographic location also were investigated using Cox proportional hazards models. The overall risk of developing prostate carcinoma during the 4-year observation period was significantly higher for the ERSPC Rotterdam cohort (5.2%) compared with the Gunma cohort (1.6%). The cumulative probability of freedom from prostate carcinoma detection and freedom from an increase in PSA levels to >/= 4.0 ng/mL (PSA progression) decreased significantly with increasing initial PSA level and did not differ significantly between Japanese and Dutch patients whose initial PSA levels fell within the same range (0.0-0.9, 1.0-1.9, 2.0-2.9, or 3.0-3.9 ng/mL). Multivariate analysis also revealed that after controlling for age and initial PSA level, the probability of PSA progression was the same for Japanese and Dutch men. Initial PSA level was the only variable found to be significantly predictive of PSA progression on multivariate analysis (P < 0.0001). The risk of developing prostate carcinoma within a given 4-year period is greater for Dutch males ages 55-69 years compared with their Japanese counterparts, because the former have higher PSA levels. Nonetheless, there appears to be no significant difference in prostate carcinoma risk between Dutch and Japanese males whose baseline PSA levels fall within the same range.