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conventionally fractionated postoperative radiotherapy demonstrated to reduce biochemical relapse in prostate adenocarcinoma (PCa), and early-salvage RT (esRT) demonstrated similar oncological results as compared with adjuvant RT (aRT), but with a safer toxicity profile. Given the PCa low α/β ratio would be of interest to evaluate the role of hypofractionation also in the postoperative setting.

the mono-institutional data of 304 PCa patients were retrospectively analyzed. 105 patients underwent aRT, 77 esRT, and 122 salvage RT (sRT). Mild-hypofractionated treatment dose in 30 fractions were 66 Gy in the aRT group, and 67.5 Gy in the salvage group. End-point of the study was the progression-free survival (PFS), biochemical relapse-free survival (BRFS), overall survival (OS) and toxicity.

the median follow-up was 33 months. The 3-year PFS and BRFS was 85.2% and 82%, respectively. The factors associated with a worst PFS at the univariate analysis (UVA) were: high Gleason score, pT≥3, esRT, concomitant hormone therapy (HT), and pelvic RT. In particular, aRT and sRT reported a significantly higher 3-year PFS compared to esRT at the UVA (93%, 85.4%, and 74.1%; p=0.000). Nevertheless, at the multivariate analysis (MVA) only Gleason score, pT and concomitant HT remains significantly correlated with PFS. Treatment of the relapse was: HT in 43% cases, stereotactic body radiotherapy (SBRT) in 43% patients, and HT+SBRT in 14% patients. At the last follow-up 8 patients deceased since, only two of which by PCa progression.

Grade 1-2 GU toxicity during RT was: urgency (36%), dysuria (23%), increased urinary frequency (12.1%), and urinary retention (11.8%). Nevertheless, the majority of symptoms were present at the baseline. Grade 3 severe toxicity was represented by 10 (3.2%) cases of incontinence and 3 (1%) cases of urgency. The incidence of any-grade RT-related GU toxicity was significantly higher in the aRT group than the salvage group (esRT + sRT) (83.8% versus 64.5%). When comparing the incidence of any-grade RT-related GU toxicity in the aRT, esRT, and sRT groups we observed a significant correlation favoring sRT, over esRT, and aRT.

mild-hypofractionated RT seems to be safe and to provide local control rates similar to conventionally fractionated regimens at three-year follow-up. Hypofractionated early-salvage radiotherapy reported similar results as the adjuvant regimen, and confirms its safer toxicity profile. No unexpected severe toxicity was reported, the majority of which were already present at the baseline.