S745
Clinical – Lower GI
ESTRO 2026
1 Division of Radiation Oncology, IEO, European Institute of Oncology, IRCCS, Milan, Italy. 2 Department of Oncology and Hemato-Oncology, University of Milan, Milan, Italy Purpose/Objective: Evaluate outcomes and toxicity profiles after re- irradiation (Re-RT) in patients with pelvic recurrence of anorectal cancer. Material/Methods: 21 anorectal cancer patients who received photon- based re-RT for pelvic recurrence between 2016 and 2025 were included. Results: The median follow-up time was 15 months. After a median of 29 months (range, 16.7-39.7) from the first RT, patients received Re-RT with a median dose of 28 Gy. The equivalent dose in 2 Gy fractions (EqD2) of Re- RT, calculated using an α / β ratio of 10 Gy, had a median of 46.4 Gy. The median GTV of re-irradiation was 51.8 cc (range: 9.71–175.62 cc).At the time of the last analysis, 12 (57.1%) patients were in local control; while the estimated local control rate at 1-year was 40.02% (IC 95%: 19.2 - 83.40).Most patients experienced only mild toxicity (grade 0–1). A single grade 2 gastrointestinal event (5%) occurred. Late toxicities were low, with 2 patients showing a GU and GI grade 1 side effects and 1 with bilateral necrosis of the femoral heads.
being more frequent in mid-low rectal tumors (65.9 % vs. 46.7 %) and predominantly gastrointestinal.
Conclusion:
Tumor location did not affect overall survival or local control; however, mid-low rectal tumors showed a higher incidence of distant metastases. This difference could be related to the lower use of TNT regimens and greater reliance on conventional chemotherapy in mid-low rectal tumors. Keywords: Chemoradiation rectosigmoid cancer
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Pelvic reirradiation in local relapse of anorectal tumors: real-world data from a single Institution Lorenzo Colombi 1,2 , Marianna Alessandra Gerardi 1 , Maria Giulia Vincini 1 , Luca Bergamaschi 1 , Chiara Lorubbio 1 , Valentina Stellari 1,2 , Martina Benincasa 1 , Luigi Cornacchia 1,2 , Francesca Emiro 1 , Barbara Alicia Jereczek-Fossa 1,2
Conclusion: Re-RT for pelvic recurrence of anorectal cancer is safe and leads to promising rates of local control with low to mild acute/early late side effects. Further investigation for patient selection is required. Keywords: reirradiation, rectum, relapse
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