LONG-TERM SALVAGE RADIOTHERAPY OUTCOME AFTER RADICAL PROSTATECTOMY AND RELAPSE PREDICTORS

Abstract

PURPOSE: We assessed the efficacy of salvage radiotherapy (SRT) and analyzed predictors of biochemical progression-free survival (bPFS) and distant metastasis-free survival in patients with clinically localized disease recurrence after radical prostatectomy. MATERIALS AND METHODS: The records of 114 patients treated with SRT at 2 institutions between 1991 and 2001 were retrospectively reviewed. Time to biochemical recurrence and to distant metastases was analyzed using the Kaplan-Meier estimation. Candidate predictors of bPFS and distant metastasis-free survival were analyzed using the log rank test and Cox regression. Acute and late complications were scored using Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer criteria. RESULTS: At a median followup of 6.3 years (range 1.9 to 13.3) for SRT 4 and 6-year bPFS was 50% (95% CI 42% to 61%) and 33% (95% CI 24% to 43%), respectively. The 6-year actuarial probability of distant metastases after SRT was 14%. Multivariate analysis demonstrated an independent association of increasing Gleason score, lymphovascular invasion and lack of a complete response to SRT with decreased 5-year bDFS. These factors were associated with significantly less 5-year distant metastasis-free survival. Pre-RT prostate specific antigen greater than 2.0 ng/ml was associated with significantly decreased 5-year bDFS and distant metastasis-free survival, although it was not maintained on multivariate analysis. CONCLUSIONS: SRT results in durable prostate specific antigen control in select patients. It is well tolerated with few severe late effects. Increasing Gleason score, lymphovascular invasion and lack of a complete response to SRT are significant risks for disease progression requiring additional management.