ESTRO 2021 Abstract Book

S595

ESTRO 2021

Conclusion Irradiation of the whole prostate with 36.25 Gy in 5 fractions and dose escalation to 50 Gy to the DIN, when combined with peri-rectal balloon spacer, was tolerable and determined as RP2D. This treatment has promising anti-tumor activity in patients with HR-PCa. QOL analysis showed minimal negative impact in GU, GI, and sexual domains. No complications were observed due the insertion of a peri-rectal balloon spacer. Compliance with protocol dose prescriptions was 100%. PD-0765 Bowel bother and function after RT for prostate cancer : the prospective QoL Pros-IT CNR study S.M. Magrini 1 , M. Noale 2 , A. Bruni 3 , L. Triggiani 4 , M. Buglione 4 , F. Bertoni 5 , L. Frassinelli 3 , R. Montironi 6 , R. Corvo' 7 , V. Zagonel 8 , A. Porreca 9 , P. Bassi 10 , M. Gacci 11 , G.N. Conti 12 , S. Maggi 13 1 University and Spedali Civili Hospital , Radiation Oncology Department, Brescia, Italy; 2 National Research Council , Neuroscience Institute - Aging Branche, Padua, Italy; 3 University Hospital of Modena, Radiotherapy Unit - Department of Oncology and Hematology, Modena, Italy; 4 University and Spedali Civili Hospital, Radiation Oncology Department, Brescia, Italy; 5 Uro-oncology Study Group , Italian Association of Radiotherapy and Clinical Oncology, Brescia, Italy; 6 Polytechnic University of the Marche Region - United Hospital of Ancona, Section of Pathological Anatomy, Ancona, Italy; 7 "Policlinio - S. Martino" Hospital and University of Genoa, Radiation Oncology Department, Genoa, Italy; 8 Veneto Institute of Oncology "IOV-IRCCS", Medical Oncology Unit, Padua, Italy; 9 Abano Terme Hospital, Department of Robotic Urological Surgery, Abano Terme (PD), Italy; 10 Catholic University of Rome - Policlinico "Gemelli", Department of Urology, Rome, Italy; 11 "Careggi" Hospital - University of Florence, Department of Urologic Robotic surgery and Renal Transplantation, Florence, Italy; 12 ASST Lariana - "S.Anna" Hospital, Urology Unit, Como, Italy; 13 National Research Council, Neuroscience Institute - Aging Branch, Padua, Italy Purpose or Objective Radiation therapy (RT) represents an important therapeutic option for the treatment of localized prostate cancer. It is known that each prostate cancer treatment is associated with specific risks and side effects which may impact patients’ health-related quality of life (QoL). The aim of the current study is to examine trajectories in patients’ reported QoL outcomes related to bowel function (BF) and bother (BB) in patients submitted to RT, associated or not to androgen deprivation therapy (ADT). Data from the longitudinal, observational PROState cancer monitoring in ITaly from the National Research Council (Pros-IT CNR) study were considered and analyzed with growth mixture models. Materials and Methods We prospectively evaluated patients’ reported outcomes (PROMs) about QoL related to BF and BB over a 2- year period from the diagnosis in 586 patients with localized or locally advanced prostate cancer submitted to radical RT, associated or not to ADT. QoL outcomes were assessed at diagnosis, 6-, 12 and 24 months using the Italian version of the University of California Los Angeles-Prostate Cancer Index (Italian-UCLA-PCI). Data on demographics, comorbidities, tumor and therapy related features were also collected. Results The responses to questions on the Italian-UCLA-PCI regarding BF and/or BB at time of diagnosis were available for 572 patients. Four hundred twenty three patients (75%) underwent IGRT, while 143 (25%) non-IGRT methods. A 3D-CRT technique was used in 186 patients (33%), IMRT in 229 (40%), VMAT in 143 (25%) and SBRT in 9 (2%). The prostate alone, the prostate+seminal vesicles, and the prostate+seminal vesicles+pelvic nodes were treated in 143, 324 and 86 patients, respectively. RT alone was used in 333 patients (59%), while ADT was administered before or during RT in 107 (18%); ADT was administered after the RT end in 135 patients (23%). The mean score at diagnosis for BF was 91.8±15.2 and 91.8±20.3 for BB. Our data revealed that the proportion of patients with persisting significant bowel worsening at the 24 months interval is very limited. Three trajectories were identified for the BF: having 3 or more comorbidities and the use of 3D-CRT technique for RT were associated with the worst trajectory (OR=3.80, 95% CI 2.04-7.08; OR=2.17, 95% CI 1.22-3.87, respectively). Two trajectories were identified for the BB scores: diabetes and the non-IGRT method were associated with being in the worst BB trajectory group (OR=1.69, 95% CI 1.06-2.67; OR=2.57, 95% CI 1.70-3.86, respectively).