Observations of prostate specific antigen doubling time in Japanese patients with nonmetastatic prostate carcinoma.

BACKGROUND: To understand better the natural history and biology of prostate carcinoma occurring in Japanese patients, the authors attempted to define changes with time in prostate specific antigen (PSA) measurements in 48 men with clinically resectable T1-T3 nonmetastatic disease. METHODS: The authors analyzed PSA changes prospectively in prostate carcinoma patients who were managed by watchful waiting. PSA doubling time was calculated by linear regression. These values and their distribution were compared with clinical parameters and with published series of prostate carcinoma patients. RESULTS: The mean age of the 48 patients at the time of diagnosis was 74.2 years. The median follow-up from the time of diagnosis was 24.0 months. The median PSA doubling time was 35.7 months. In 27.1% of patients, there was no increase in the PSA level over the observation period. A rapid rise in PSA (doubling time of <2 years) was observed in 29.2% of patients. These results in Japanese patients are virtually the same as those reported in Western countries. There was no statistically significant relation between calculated PSA doubling time and clinical disease stage, tumor grade, PSA level at the time of diagnosis, probability of extraprostatic disease, patient age at diagnosis, or prostate volume (P > 0.05). CONCLUSIONS: Prostate carcinoma may not differ significantly by race once it becomes clinically manifest. The magnitude of positive changes in PSA over a given period of observation may not be helpful in determining the need for therapy. The previously reported incidence of clinically insignificant prostate carcinoma, which primarily was based on pathologic findings in surgical specimens, may have been an underestimation.