High-Grade Late Urinary Toxicity Following Salvage Radiotherapy After Radical Prostatectomy: A Retrospective Cohort Study

Purpose: To find out the incidence and predictors for late high-grade genitourinary (GU) toxicity following salvage radiotherapy (SRT), we investigated the consecutive patients who were treated with SRT after radical prostatectomy.Materials and Methods: Patients who underwent SRT for biochemical recurrence after radical prostatectomy were reviewed. The incidence of GU toxicity was assessed and risk factors for grade ≥2 and ≥3 GU toxicity were evaluated. The STROBE (STrengthening the Reporting of OBservational studies in Epidemiology) guided the reporting of this study.Results: Among the total of 217 patients, 88 patients (40.5%) showed late grade ≥2 GU toxicity. The incidence of late grade ≥3 GU toxicity was 11.5%. The presence of grade ≥2 baseline GU dysfunction (hazard ratio [HR], 6.097; 95% confidence interval [CI], 3.280–11.333; p<0.001) and short interval (<1 year) from surgery to SRT (HR, 1.994; 95% CI, 1.182–3.365; p=0.01) were associated with late grade ≥2 GU toxicity. A short interval from surgery to SRT was an independent predictor of late grade ≥3 GU toxicity (HR, 2.975; 95% CI, 1.135–7.794; p=0.027).Conclusions: The incidence of late high-grade GU toxicity was not uncommon after SRT. Thus, care should be taken when we consider SRT in patients with baseline urinary dysfunction and a short interval from surgery to SRT, to determine an optimal treatment strategy with balancing quality of life and oncologic outcome of patients.