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

Abstract

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. 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. 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. 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.