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

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.

Data of 107 patients (median age 65 years) with persistent (>0.1 ng/mL) or rising prostate-specific antigen after radical prostatectomy were retrospectively analyzed. The mean dose to clinical target volume was 70 Gy in 32 fractions (the equivalent dose in 2 Gy fraction is 73.2 Gy 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.

The median follow up was 37 months (range 6-126 months). 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 (≥0.5 ng/mL, <0.5 ng/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 grade 2 in 13% and grade 3 in 6% of patients. The highest late gastrointestinal toxicities were grade 2 in 6% and grade 3 in 3% of patients.

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.