Radiation Therapy After Radical Prostatectomy: Impact on Metastasis and Survival

Abstract

Although secondary radiation therapy decreases the risk of biochemical progression after radical prostatectomy, its impact on metastasis and survival is less well established. We evaluated the impact of adjuvant and salvage radiotherapy on clinical progression and mortality. A total of 361 patients who received adjuvant radiation were matched based on clinicopathological features to patients who did not receive adjuvant radiation in a 2:1 case-control ratio. Postoperative survival was estimated using the Kaplan-Meier method and compared using the log rank test. A second cohort of 2,657 men who experienced biochemical recurrence after prostatectomy was separately evaluated. Cox proportional hazard regression models were used to analyze the impact of salvage radiotherapy on disease progression and survival. Adjuvant radiotherapy was associated with significantly improved 10-year biochemical recurrence-free survival (63% vs 45%, p <0.001), local recurrence-free survival (97% vs 82%, p <0.001) and a decreased need for late hormone therapy (17% vs 28%, p = 0.002) but did not impact systemic progression and overall survival (p = 0.94 and 0.27, respectively). Of the 2,657 patients who experienced biochemical recurrence after surgery 856 (32.3%) received salvage radiation. On multivariate analysis salvage radiotherapy decreased the risk of local recurrence (HR 0.13, 95% CI 0.06-0.28, p <0.0001) and delayed hormonal therapy (HR 0.81, 95% CI 0.71-0.93, p = 0.003) and systemic progression (HR 0.24, 95% CI 0.13-0.45, p <0.0001) but did not significantly impact mortality (p = 0.48). Adjuvant and salvage radiation provide long-term local control and decrease the need for delayed hormonal therapy but neither improves survival. These results must be weighed against the potential morbidity of postoperative radiation when counseling patients.