Prediction of response to salvage radiation therapy in patients with prostrate cancer recurrence after radical prostatectomy

Purpose: To identify factors predictive of local recurrence as defined by a complete response to salvage radiation therapy in patients whose disease r ecurs after radical prostatectomy. Patients and Methods: Ninety-five patients with recurrence after radical pr ostatectomy who were evaluated by prostatic fossa biopsies, and a subset of 49 of these patients treated with radiation for control of presumed or bio psy-proven local recurrence, were studied. Results: Biopsies were positive in 40 (42%) of the 95 biopsied patients. Mu ltivariate analysis revealed that prebiopsy prostate-specific antigen (PSA) level, postrecurrence PSA doubling rime, and positive digital rectal exami nation (DRE) of the prostatic fossa were all statistically significant pred ictors 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 show ed no differences in the PSA relapse-free probabilities associated with any pathologic features of the radical prostatectomy specimen, biopsy confirma tion of local recurrence, or DRE of the prostatic fossa. In multivariate an alysis, controlling for all other variables, preradiation PSA and postrecur rence PSA doubling time measured before radiation were the only statistical ly significant predictors of outcome. Conclusion: DRE of the prostatic fossa, prebiopsy PSA, and postrecurrence P SA doubling time predict which patients will have biopsy-proven local recur rence. However, response to salvage radiation therapy is associated with po strecurrence PSA doubling time and with preradiation PSA level only. DRE of the prostatic fossa and biopsy confirmation of local recurrence are not as sociated with salvage radiation outcome.