Adverse risk factors for salvage radiotherapy outcomes after radical prostatectomy in prostate cancer patients

PURPOSE

To investigate salvage treatment approaches and treatment outcomes in high-risk prostate cancer after radical prostatectomy (RP).

METHODS

In this retrospective, multicenter study, 272 patients who underwent salvage radiotherapy (RT) ± androgen deprivation therapy (ADT) for recurrent prostate cancer after RP between 2007 and 2021 were analysed. Univariate analyses of time to biochemical and clinical relapse after salvage therapies were conducted using Kaplan-Meier plots and log-rank tests. Multivariate analyses were performed using a Cox proportional hazards model to determine the risk factors for disease relapse.

RESULTS

Median age was 65 (48-82) years. All patients underwent salvage prostate bed RT. Pelvic lymphatic RT was performed in 66 patients (24.3%) and ADT was included in 158 (58.1%) patients. The median PSA value before RT was 0.35 ng/mL. The median follow-up time was 64 (12-180) months. 5-years bRFS, cRFS, and OS were 75.1%, 84.8%, and 94.9% respectively. In multivariate cox regression analysis; seminal vesicle invasion (HR 8.64, 95% CI 3.47-21.48, p < 0.001), pre-RT PSA higher than 0.14 ng/mL (HR 3.79, 95% CI 1.47-9.78, p = 0.006), and ≥ 2 positive pelvic lymph nodes (HR 2.50, 95% CI 1.11-5.62, p = 0.027) were found to be unfavorable prognostic factors for bRFS.

CONCLUSION

Salvage RT ± ADT provided 5-years biochemical disease control in 75.1% of patients. Seminal vesicle invasion, ≥ 2 positive pelvic nodes and delayed administration of salvage RT (PSA levels higher than 0.14 ng/mL) were found to be adverse risk factors for relapse. Such factors should be taken into account during the decision process on salvage treatment.