Partial prostate re-irradiation for the treatment of isolated local recurrence of prostate cancer in patients previously treated with primary external beam radiotherapy: short-term results of a monocentric study.

ABSTRACT

Many different therapeutic options are available for locally recurrent prostate cancer (PCa). However, standard treatment has not yet been established. We conducted a partial prostate re-irradiation (PPR) program for the treatment of isolated and limited-size intraprostatic recurrences, in patients who previously underwent external beam radiation therapy (EBRT) as primary treatment for prostatic cancer (PCa). The analysis of this experience in terms of feasibility, toxicity, and efficacy is reported. The inclusion criteria of this retrospective analysis were previous definitive EBRT, evidence of biochemical recurrence, radiological detection of isolated local relapse, and PPR as local salvage therapy. Gastrointestinal (GI) and genitourinary (GU) toxicities were registered according to the RTOG/EORTC criteria. Between July 2012 and May 2019, 44 patients were treated with PPR. All patients completed the planned treatment. The median follow-up was 25.4 months. Tumor progression was observed in 18 patients (40.9%). Two-year local control, biochemical failure-, and clinical relapse-free survival rates were 90.1%, 58.3%, and 67.9%, respectively. The occurrence of biochemical failure after PPR is lower for patients with the time interval between the primary EBRT and first biochemical failure >4 years; local control results strongly associated with a biologically effective dose (BED) at first EBRT >177 Gy. No acute grade 3 or greater toxic events were observed. Two late grade 3 GU toxicities were reported. Although retrospective in design, our study indicates that PPR appears as a feasible, well-tolerated, and effective salvage treatment for isolated local PCa recurrence. Long term data are required in order to confirm these results.