Adjuvant Radiotherapy in Prostate Cancer: Predictors of Prostate-Specific Antigen Recurrence from the CaPSURE Database

Abstract

To analyze an observational database of prostate cancer, assessing for patterns of use and predictors of prostate-specific antigen (PSA) recurrence after adjuvant radiotherapy (RT). From the Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE), 5336 men underwent prostatectomy from 1989 to 2004. Of these 5336 men, 96 men (1.8%) underwent adjuvant RT. These 96 men were classified as having low (Stage T1c-T2a and PSA level of 10 ng/mL or less and Gleason score of 6 or less), intermediate (Stage T2b or PSA level greater than 10 ng/mL and 20 ng/mL or less or Gleason score 7), or high (Stage T2c or higher or PSA level greater 20 ng/mL or Gleason score of 8 or greater) risk of PSA recurrence. PSA recurrence was defined as two consecutive PSA levels greater than 0.2 ng/mL. Differences between patients who experienced failure were assessed by chi-square tests or analysis of variance. Univariate and multivariate analyses were performed using a Cox proportional hazard regression model. Of the 96 men, 27 (28%) experienced PSA failure and 20 (21%) received additional treatment, with a median of 60 months of follow-up. The clinical risk group (P <0.01), PSA level at diagnosis (P <0.01), Gleason score (P <0.01), and seminal vesicle invasion (P <0.01) all significantly associated with PSA recurrence. The clinical risk group was the sole predictor of PSA recurrence-free survival on multivariate analysis (hazard ratio 2.4, 95% confidence interval 1.7 to 8.3, P = 0.007). Adjuvant RT was not frequently used in men enrolled in CaPSURE. PSA recurrence was observed more frequently in men with high-risk disease, suggesting that adjuvant RT is not adequate therapy and that these men might benefit from the combined use of hormonal therapy and RT.