Improved freedom from PSA failure with whole pelvic irradiation for high-risk prostate cancer

Purpose: To determine the impact of whole pelvic irradiation on the risk of PSA failure in prostate cancer patients, at high predicted risk for lymph node involvement, receiving definitive radiotherapy. Materials and Methods: Between October 1987 and December 1995, 506 patients with clinically localized prostate cancer were treated with definitive rad iotherapy at UCSF and affiliated institutions. Treatment consisted of 4-fie ld whole pelvic irradiation followed by a prostate-only boost, or prostate- only treatment (median follow-up was 35 months and 30 months, respectively) . PSA failure was defined as: 1. a PSA value greater than or equal to 1 ng/ ml; or 2. a PSA value that rose greater than or equal to 0.5 ng/ml in less than or equal to 1 year posttreatment on two consecutive measurements, with the first rise defined as the time of failure. The calculated risk of lymp h node positivity (%rLN+) was defined as 2/3(iPSA) + 10(GS-6), and high ris k was defined as %rLN+ greater than or equal to 15%. Univariate and multiva riate analyses were performed. Results: A total of 201 high-risk patients were identified. High-risk patie nts who received whole pelvic irradiation had significantly improved freedo m from PSA failure compared to those who received prostate-only treatment ( median PFS = 34.3 months vs. 21.0 months; p = 0.0001). Potential confoundin g variables, including initial PSA, Gleason score, T stage, radiation dose, year of treatment, use of three-dimensional (3D) conformal techniques, and use of hormone therapy, did not account for the observed difference in tim e to PSA failure. Multivariate analysis revealed type of radiation treatmen t to be the most significant independent predictor of outcome. Conclusion: Whole pelvic radiotherapy significantly improves the PSA failur e-free survival in patients with a high calculated risk of lymph node posit ivity. (C) 1998 Elsevier Science Inc.