External validation of the UCSF-CAPRA (University of California, San Francisco, Cancer of the Prostate Risk Assessment) in Japanese patients receiving radical prostatectomy.

OBJECTIVE: In 2005, the University of California, San Francisco developed the Cancer of the Prostate Risk Assessment (UCSF-CAPRA) score as a new risk stratification tool. The UCSF-CAPRA, which ranges from 0 to 10 points, consists of five clinical variables, prostate-specific antigen, Gleason score, T stage, percent of positive biopsies and age. The aim of this study was to validate the UCSF-CAPRA score for Japanese prostate cancer patients receiving radical prostatectomy using the contemporary Gleason grading.
METHODS: From 1999 to 2010, 211 men who underwent radical prostatectomy were used for validation. Biochemical progression-free survival was calculated using the Kaplan-Meier method and the UCSF-CAPRA and D'Amico risk categories were compared using the log-rank method. The concordance index (c-index) for the UCSF-CAPRA and D'Amico risk classification was calculated.
RESULTS: Using the UCSF-CAPRA score, 85 (40.3%), 106 (50.2%) and 20 (9.5%) subjects were stratified as 0-2 points (low risk), 3-5 points (intermediate risk) and 6-10 points (high risk). Using the D'Amico risk criteria, 66 (31.3%), 89 (42.2%) and 56 (26.5%) were stratified as low-, intermediate- and high-risk groups, respectively. The Kaplan-Meier analysis showed that the UCSF-CAPRA divided the patients significantly into each risk category. There was no significant difference between low and intermediate in the D'Amico risk classification. The c-index of the UCSF-CAPRA and D'Amico classification was 0.755 and 0.713, respectively.
CONCLUSION: The UCSF-CAPRA is an acceptable risk category tool comparable to that of the D'Amico risk classification for Japanese prostate cancer patients receiving radical prostatectomy in the contemporary Gleason grading era.