Salvage intensity modulated radiotherapy using endorectal balloon after radical prostatectomy: Clinical outcomes

Objectives: To evaluate biochemical non-evidence of disease and adverse events of salvage intensity-modulated radiotherapy using an endorectal balloon for prostate cancer patients after radical prostatectomy. Methods: Data of 107 patients (median age 65 years) with persistent (>0.1ng/mL) or rising prostate-specific antigen after radical prostatectomy were retrospectively analyzed. The mean dose to clinical target volume was 70Gy in 32 fractions (the equivalent dose in 2Gy fraction is 73.2Gy based on α:β=2). Biochemical non-evidence of disease and predictive factors were assessed. Genitourinary toxicity and gastrointestinal toxicity were also evaluated using the Radiation Therapy Oncology Group toxicity criteria. Results: The median follow up was 37months (range 6-126months). A total of 48 patients developed biochemical recurrence. The 3- and 5-year biochemical non-evidence of disease rates of all patients were 52.6% and 48.8%, respectively. The Gleason score (≥4+3, ≤3+4) and pre-intensity-modulated radiotherapy prostate-specific antigen level (≥0.5ng/mL, <0.5ng/mL) were significant predictive factors for biochemical non-evidence of disease in univariate analysis. In multivariate analysis, only the Gleason score was detected as a significant variable. The highest late genitourinary toxicities were grade2 in 13% and grade3 in 6% of patients. The highest late gastrointestinal toxicities were grade2 in 6% and grade3 in 3% of patients. Conclusion: Despite a relatively high radiation dose, intensity-modulated radiotherapy with an endorectal balloon can be delivered with acceptable toxicity and efficacy for patients developing biochemical recurrence after radical prostatectomy.