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Ultra Hypofractionated Radiation therapy (UHRT) represents a curative-intent treatment option in the management of localized prostate cancer (PCa), with disease progression and cancer-specific death rates comparable to radical surgery. The purpose of the present work is to report updated toxicity and oncological results at five years of Phase II prospective trial "Short-term high precision radiotherapy for early prostate cancer with a simultaneous boost to the dominant intraprostatic lesion (DIL) for patients with early-stage PCa”. The aim of the study is to identify clinically meaningful information through the analysis of validated questionnaires testing gastrointestinal (GI) and genitourinary (GU) RT-related toxicity and their impact on quality of life (QoL).

As part of the AIRC IG-13218 (NCT01913717), we analyzed data from patients with low- and intermediate-risk PCa treated with UHRT and simultaneous boost to the DIL. At the end of RT treatment, clinical assessment and prostate-specific antigen (PSA) measurements were performed every 3 months for at least 2 years and GI and GU toxicities were evaluated contextually. QoL of enrolled patients was assessed by the International Prostate Symptoms score (IPSS), European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire—Core 30 (EORTC QLQ-C30), EORTC QLQ prostate-specific (QLQ-PR25), and sexual activity by International Index of Erectile Function (IIEF-5). Patients’ score changes were calculated at the end of RT, at one, 12 and 60 months after RT

At a median follow-up of 5.1 years (range 3.8-6.8 years), 7 patients died for other cancer causes, 3 patients experienced a clinical relapse of disease and for 45 patients updated data were available. Disease-free survival at 5 years was 82% with a median last PSA of 0.37 ng/ml. At the last follow-up, 32 QoL questionnaires were collected. Extensive analysis of different QoL and toxicity assessments showed that patients’ tolerance was satisfactory across all the considered time points, with a statistically significant improvement of QoL, IPSS and bowels symptoms from baseline to the last follow-up (p= .002, p=.004, p=.02, respectively) (Figure 1). Six grade (G)1 and two G2 gastrointestinal (GI) and one G1 and two G2 genitourinary (GU) toxicities were reported at the last follow-up, and no G≥3 events were reported.

These updated data about efficacy and late toxicity confirm our previously published findings that the UHRT schedule with a concomitant boost on the DIL is a safe and effective approach. The increasing dose to the DIL does not worsen the RT toxicity and consequently does not affect patients' QoL, thus opening the possibility of an, even more, escalated treatment.