Long-term outcomes of salvage radiotherapy for PSA-recurrent prostate cancer: validation of the Stephenson nomogram.

ABSTRACT

PURPOSE: Approximately one-third of patients who undergo radical prostatectomy for clinically localized prostate cancer will ultimately develop a biochemical recurrence. We report our long-term outcomes of salvage radiotherapy (SRT), and in so doing, validate a recently published prognostic nomogram. METHODS: A retrospective chart review was performed of all patients treated with SRT following radical prostatectomy for biochemical PSA recurrence at our institution between 1992 and 2003. We calculated the probability of 6-year biochemical progression-free survival following SRT and performed a goodness-of-fit test to ascertain whether the previously published nomogram correctly predicted our observations. RESULTS: During the study period, 96 patients were treated with SRT. At a median follow-up of 71 months, 44 (46%) had a durable PSA-free response. There was no significant difference between the observed progression-free survival and that predicted by the Stephenson nomogram (P = 0.7). Multivariate logistic regression analysis determined that PSA value at the initiation of SRT (P = 0.02) and pathologic Gleason Score (P = 0.04) were significantly associated with the probability of recurrence. CONCLUSIONS: During the study period, nearly half of patients treated with SRT for PSA recurrence following radical prostatectomy had a durable treatment response. We found the predictive nomogram developed by Stephenson, et al. to be valid when tested on our independent cohort of patients.