ESTRO 2025 - Abstract Book

S1265

Clinical – Lower GI

ESTRO 2025

validated EORTC QLQ-ANL27 providing unique data describing patient experience during and after chemoradiotherapy.

Keywords: anal cancer, radiotherapy, toxicity

References: 1. Osoba D, Rodrigues G, Myles J, Zee B, Pater J. Interpreting the significance of changes in health-related quality-of life scores. J Clin Oncol. 1998;16(1):139-44. 2. Gilbert at al. Standard vs dose reduced chemoradiotherapy in anal cancer: short-term results of the PLATO-ACT4 RCT. Abstract OC-0831, ESTRO 2203 Annual meeting

3960

Digital Poster overdosed boost (SIB) of radiotherapy on locally advanced rectal cancer Donatella Caivano 1,2 , Stefano Mossa 3 , Maurizio Valeriani 3 , Vitaliana De Sanctis 3 , Daniela Musio 2 , Mattia Falchetto Osti 3 1 Department of Medical and Surgical Sciences and Translational Medicine, Traslational Medicine and Oncology Faculty of Medicine and Psycology, Sapienza University of Rome, Rome, Italy. 2 Department of Radiation Oncology, San Giovanni Addolorata Hospital, Rome, Italy. 3 Department of Radiation Oncology, Sant’ Andrea Hospital, Rome, Italy Purpose/Objective: Aim of this study is to evaluate local control (LC), progression-free survival (PFS) and overall survival (OS) in patients with locally advanced rectal cancer treated preoperatively with a simultaneous integrated overdosed boost (SIB) of radiotherapy with VMAT/IGRT and concurrent chemotherapy. Material/Methods: This is an observational single institution retrospective study. From March 2022 to May 2024, we treated 24 patients with locally advanced rectal cancer with preoperative CRT. Patients unable to receive TNT due to comorbidity or patients with non-bulky disease were candidates for a course of radiotherapy of 45 Gy in 25 fractions to the pelvis and 57.5 Gy in 25 fractions as a boost to the macroscopic rectal disease and positive lymph nodes. A pre-treatment cone beam was administered before each fraction. The technique used was VMAT. Patients received capecitabine 825 mg/m² as concurrent chemotherapy. Results: The LC at 1 and 2 years was 78% and 78% respectively. On univariate analysis we found a significant statistical correlation with age and PS ECOG, (p: 0.0383 and p < 0.0001 respectively). PFS at 1 and 2 years was 88% and 88% respectively. On univariate analysis we found a significant statistical correlation with PS ECOG <0.0001. OS at 1 and 2 years was 100% and 75% respectively. At univariate analysis we have not found a significant statistical correlation. As toxicity we have noted only one case of late toxicity G3 (GI and GU) characterised whit an anal fistula and dysuria Conclusion: This is a study with a simple size of patients analysing an overdose of boost to macroscopic disease with 57.5 Gy in 25 fractions in patients with locally advanced rectal cancer. The results are promising and longer follow-up may be necessary to better evaluate the response to this type of treatment and toxicities.

Keywords: rectal cancer, SIB, VMAT