ESTRO 2025 - Abstract Book

S1281

Clinical – Lower GI

ESTRO 2025

Purpose/Objective: Treatment strategies in locally recurrent rectal cancer (LRRC) have been increasingly debated and balanced against previous treatments received for the primary rectal cancer. Reirradiation could be useful to achieve curative surgery but at the cost of peri-operative morbidity and sequelae. The aim of this randomized trial was to assess the efficacy of neoadjuvant chemotherapy followed by pelvic reirradiation versus neoadjuvant chemotherapy alone on the rate of curative surgery (R0) in previously irradiated pattients with LRRC. Material/Methods: GRECCAR 15 (NCT03879109) is a prospective, multicentre, open-label, outcome assessor-blinded, superiority randomized controlled phase III clinical trial. The neoadjuvant CT regimen was FOLFIRINOX (6cycles), and the pelvic reirradiation consists of conformal intensity-modulated radiotherapy (30.6 Gy/17 fractions) with concomitant capecitabine,1600 mg/m²/day, five days a week. The primary outcome was the R0 resection rate. Results: From July 2019 to April 2022, 58 patients were included among 186 planned (inclusions closed in december 2022 because of low accrual). The mean size of the LRRC was 5.1 cm involving posterior and lateral pelvic compartments in more than 80% of cases without significant difference between the 2 groups. Compliance to neoadjuvant CT was similar in both groups with a median number of 5(4-6) cycles received. In the reirradiation group, all patients received the full radiotherapy dose, and only 2 patients experienced RT interruption >3 days. Among 46 patients operated, surgical procedures were pelvic exenteration in 55%, extended-TME in 34% and TME in 11%, with vascular and bone resection in 29% and 58%, respectively. The R0 resection rate was 56.5% (IC95% [34.5-76.8]) in the reirradiation arm compared to 52.2% (IC95%[30.6-73.2]) in the CT arm. Perioperative morbidity grade ≥ 3 according to Dindo-Clavien score occured in 31.7 % of patients in both arms. Conclusion: The GRECCAR15 randomized phase 3 trial showed the feasibility of reirradiation as preoperative treatment for locally recurrent rectal cancer without increasing perioperative morbidity but failed to improve R0 resection with respects to the low number of patients included. References: 1- Holman FA, et al. Results of a pooled analysis of IOERT containing multimodality treatment for locally recurrent rectal cancer: Results of 565 patients of two major treatment centres. Eur J Surg Oncol 2017;43:107-117. 2- van der Meij W, et al. Treatment of locally recurrent rectal carcinoma in previously (Chemo)Irradiated patients: A review. Dis Col Rectum 2016;59:148-156. 3- Denost Q, et al. French current management and oncological results of locally recurrent rectal cancer. Eur J Surg Oncol 2015; 41:1641-1652. 4- Beyond TME Collaborative. Consensus statement on the multidisciplinary management of patients with recurrent and primary rectal cancer beyond total mesorectal excision planes. Br J Surg 2013; 100:1009-1014. Keywords: Reirradiation, rectal cancer, pelvic recurrence

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Digital Poster Real-world clinical results of total neoadjuvant therapy in locally advanced rectal cancer: a single institution study over four years Zsofia Egyud 1 , Linda Varga 1 , Laszlo Torday 1,2 , Emese Fodor 1 , Zoltan Varga 1 , Arpad Puskas 1 , Szilvia Gaal 1 , Azizov Rufat 1 , David Toth 1 , Timea Rozsvai 1 , Eva Pusztai 1 , Emoke Borzasi 1 , Zoltan Vegvary 1 , Bela Vasas 3 , Anita Sejben 3 , Zsolt Berenyi 4 , Gyorgy Lazar 5 , Attila Paszt 5 , Balazs Panczel 5 , Klara Lemes 6 , Katalin Hideghety 1 , Judit Olah 1 , Aniko Maraz 1