PROLAPSE: survey about local prostate cancer relapse salvage treatment with external beam re-irradiation: results of the Italian Association of Radiotherapy and Clinical Oncology (AIRO)

Purpose We herein present the results of the first Italian Association of Radiotherapy and Clinical Oncology (AIRO) survey regarding salvage external beam re-irradiation of local prostate cancer relapse named PROLAPSE. Methods A questionnaire with 12 items was administered to the 775 Italian radiation oncologist members of the AIRO. Results One hundred of the members completed the survey. The survey highlighted that 59% of the participants are currently performing prostate re-EBRT, while nearly two-thirds (65%) affirmed that they are taking into consideration the procedure in case of intraprostatic relapse. Regarding the clinical target volume (CTV), only a minority (16%) declared to always prefer the partial prostate re-irradiation, while a consistent portion (nearly two-thirds) relied on clinical considerations of the choice towards partial or whole gland irradiation. The main techniques used for re-irradiation resulted to be intensity-modulated RT (IMRT)/volumetric modulated arc therapy (VMAT) and SBRT, having received approximately 40% of responses each. Regarding the criteria for patients' selection, more than 75% of responders agreed on the use of positron emission tomography (PET)/computed tomography (CT)-choline to exclude distant metastases and of multiparametric magnetic resonance imaging (mp-MRI) to detect intraprostatic recurrence. A sufficient timeframe (> 3 years) between primary RT and reirradiation was indicated by more than half of participants as an important driver in decision-making, while histological confirmation of the relapse was considered not essential by more than two-thirds. For the use of concomitant androgen deprivation therapy (ADT), most AIRO members (79%) agreed that the prescription should be based on a case-by-case analysis. Extreme hypofractionation (> 5 Gy/fraction) was preferred by the majority (52%) of the AIRO members. In most centers (more than 74%), the planning dose-volume constraints were generally extrapolated from the published data. In half of the cases, the interviewed responders affirmed that no major gastrointestinal (GI) and genitourinary (GU) toxicities were registered in the follow-up of their re-EBRT patients. Bladder complications represented the most commonly observed form of toxicity, with an incidence of 67%. Conclusion This first AIRO survey about salvage prostate re-EBRT provides an interesting snapshot and suggests increasing interest in re-EBRT patients in Italy. Consensus about some aspects of patients' selection, the necessity of biopsy, fractionation, and highly selective techniques seems feasible, but other key points such as irradiated volume, dosimetry parameters, and hormonal treatment association need to be clarified.