ESTRO 2021 Abstract Book

S600

ESTRO 2021

Regionale Parini-AUSL Valle d’Aosta, Radiotherapy, Aosta, Italy; 3 IRCCS Istituto Nazionale dei Tumori “Regina Elena, Radiotherapy, Rome, Italy; 4 Ospedale di Ivrea, Radiotherapy, Ivrea, Italy; 5 Azienda Sanitaria dell’Alto Adige, Radiotherapy, Bolzano, Italy; 6 Fondazione IRCCS Istituto Nazionale dei Tumori, Radiotherapy, Milan, Italy; 7 Cliniche Gavazzeni Humanitas, Radiotherapy, Bergamo, Italy; 8 IRCC Candiolo, Radiotherapy, Milan, Italy; 9 Ospedale degli Infermi, Radiotherapy, Biella, Italy; 10 Azienda Ospedaliero Universitaria S. Maria della Misericordia, Radiotherapy, Udine, Italy; 11 A.O. SS. Antonio e Biagio, Radiotherapy, Alessandria, Italy; 12 IRCCS Istituto Nazionale dei Tumori “Regina Elena", Radiotherapy, Rome, Italy; 13 Cliniche Gavazzeni, Rasiotherapy, Bergamo, Italy; 14 Fondazione IRCCS Istituto Nazionale dei Tumori - Prostate Program, Radiotherapy, Milan, Italy; 15 San Raffaele Scientific Institute, Radiotherapy, Medical Physics, Milan, Italy; 16 Fondazione IRCCS Istituto Nazionale dei Tumori, Prostate Program - Università degli Studi Milano, Radiotherapy, Milan, Italy; 17 San Raffaele Scientific Institute - Università Vita Salute San Raffaele, Radiotherapy, Milan, Italy; 18 San Raffaele Scientific Institute, Radiotherapy, Milan, Italy; 19 San Raffaele Scientific Institute, R, MILANO, Italy Purpose or Objective An ongoing, registered, multi-Institute observational study is assessing the patient-reported (PRO) intestinal toxicity (IT) from IMRT whole-pelvis radiotherapy (WPRT) in the radiation treatment of prostate cancer, regardless of its intent. This analysis aims to describe the PRO acute IT and its detrimental effect on Emotional (EMOT), Social (SOC) and Systemic (SYST) Domains. Materials and Methods The median EQD2 (α/β ratio 3 Gy) to the prostate, prostatic bed and lymph-nodal PTV was 80.03, 72.58 and 51.14 Gy, respectively. IT was measured by means of the Inflammatory Bowel Disease Questionnaire (IBDQ), including 10 items evaluating the BOWEL Domain and 3 additional QoL scales analyzing the detrimental impact of IT on EMOT, SOC and SYST. In IBDQ scales (range 1-7), lower scores indicate worse situation. This analysis focused on 608 pts, enrolled from 2011 to 2020, with complete BOWEL scale at baseline, RT mid-point and end. The maximum decrease (=worsening, D worst) between baseline and RT mid-point or end of the ten BOWEL symptoms as well of EMOT, SOC and SYST Domains was assessed. In addition, the detrimental impact of a large number of clinical (including the baseline ten BOWEL symptoms, their D worst, and personality traits as measured by the EPQR questionnaire) and treatment-related variables, including ADT, RT doses and intent, on the impairment of EMOT, SOC and SYST (n=597, 593 and 607, respectively), was investigated. The 25 th percentile of EMOT, SOC and SYST Domains D worst with respect to baseline were set as end-points for logistic multivariable analyses (including only variables with a p-value <0.20 at univariable analysis) investigating the independent predictors of moderate/severe impairment of EMOT, SOC and SYST Domains. Results Overall, the RT-induced acute IT was mild, with only 4/10 BOWEL symptoms exhibiting a median D worst ≥-1 point: Loose Bowel Movement, Gas Passage and Urge to Defecate (IBDQ items # 2, 17 and 24, respectively, D worst -1) and Frequent Bowel Symptoms (IBDQ #1, D worst -2, Table 1a). The median D worst of the remaining six BOWEL symptoms was zero (Table 1a).

The corresponding median D worst of EMOT, SOC and SYST were equally scanty, ranging from -0.25 to -0.60 (Table 1b). The acute worsening of Frequent Bowel Symptoms independently affected SYST, but not EMOT and SOCIAL, worsening. The WPRT-induced increase of Gas Passage and Urge to Defecate, but also of Abdominal Pain, Rectal Bleeding and Nausea/Feeling Sick, whose WPRT-induced worsening was apparently only minimal,