Prediction of Response to Salvage Radiation Therapy in Patients With Prostate Cancer Recurrence After Radical Prostatectomy

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Abstract
PURPOSE: To identify factors predictive of local recurrence as defined by a complete response to salvage radiation therapy in patients whose disease recurs after radical prostatectomy. PATIENTS AND METHODS: Ninety-five patients with recurrence after radical prostatectomy who were evaluated by prostatic fossa biopsies, and a subset of 49 of these patients treated with radiation for control of presumed or biopsy-proven local recurrence, were studied. RESULTS: Biopsies were positive in 40 (42%) of the 95 biopsied patients. Multivariate analysis revealed that prebiopsy prostate-specific antigen (PSA) level, postrecurrence PSA doubling time, and positive digital rectal examination (DRE) of the prostatic fossa were all statistically significant predictors of a positive biopsy. For the 49 patients subsequently treated with salvage radiation therapy, the overall actuarial 3- and 5-year PSA relapse-free probabilities were 43% and 24%, respectively. Univariate analysis showed no differences in the PSA relapse-free probabilities associated with any pathologic features of the radical prostatectomy specimen, biopsy confirmation of local recurrence, or DRE of the prostatic fossa. In multivariate analysis, controlling for all other variables, preradiation PSA and postrecurrence PSA doubling time measured before radiation were the only statistically significant predictors of outcome. CONCLUSION: DRE of the prostatic fossa, prebiopsy PSA, and postrecurrence PSA doubling time predict which patients will have biopsy-proven local recurrence. However, response to salvage radiation therapy is associated with postrecurrence PSA doubling time and with preradiation PSA level only. DRE of the prostatic fossa and biopsy confirmation of local recurrence are not associated with salvage radiation outcome.