ESTRO 2025 - Abstract Book

S1165

Clinical – Lower GI

ESTRO 2025

In this retrospective analysis, we reviewed the medical records of newly diagnosed LARC patients aged 18–75 years who underwent curative treatment at our center from January 2017 to December 2023. The treatment protocol involved NACRT (50.4Gy in 28 fractions with concurrent Capecitabine), followed by TME and ACT. Of the 157 patients who underwent NACRT, 47 who completed the entire course of treatment at our centre were selected for analysis. Clinical data, including patient demographics, diagnosis, treatments, and outcomes, were collected from medical records and analysed descriptively. The primary endpoint was overall survival (OS), defined as the time from the initiation of NACRT to death from any cause. The secondary endpoint was disease-free survival (DFS), defined as the time from the initiation of NACRT to the first documented event of progression or death. Both endpoints were analyzed using Cox regression and summarized with Kaplan-Meier curves. Results: Of the 47 patients analyzed, 89% presented with stage III disease. Regarding ACT, 75% received the CAPOX regimen, while 19% were treated with FOLFOX. With a median follow up of 2.5 years (IQR 0.9-7.8 years), the 3-year OS was 78.1% (95% CI: 64.5%–94.7%), and the 5-year OS was 66.8% (95% CI: 49.9%–89.4%). The 3-year DFS was 71.7% (95% CI: 57.1%–90.0%), and the 5-year DFS was 66.9% (95% CI: 50.8%–87.2%). Conclusion: The 3-year OS and DFS in our study were comparable to those reported in the standard arm of recent total neoadjuvant therapy (TNT) trials for LARC 2 . These findings highlight the potential of adopting TNT as the standard approach to improve treatment outcomes in this patient population.

Keywords: Rectal cancer, radiotherapy, chemotherapy.

References: 1. Scott AJ, Kennedy EB, Berlin J, et al. Management of Locally Advanced Rectal Cancer: ASCO Guideline. J Clin Oncol . 2024;42(28):3355-3375. 2. Hui C, Vitzthum LK, Chang DT, Pollom EL. Neoadjuvant Therapy in the Post-German Rectal Trial Era: Making Sense in the Absence of Consensus. Pract Radiat Oncol . 2023;13(1):e54-e60.

1299

Digital Poster Surgery after neo-adjuvant long course radiotherapy in locally advanced rectal cancer : timing matters . A retrospective matched paired control study. Grazia Lazzari 1 , Greta Di Stefano 2 , Barbara D'Andrea 1 , Antonietta Montagna 1 , Ilaria Benevento 1 , Giovanni Castaldo 1 , Luciana Rago 1 , Angela Pia Solazzo 1 , Emanuela Botte 3 , Aldo Cammarota 3 , Pasqualina Modano 4 , Alessio Vagliasindi 2 1 Radiation Oncology Unit, IRCCS-CROB, Rionero in Vulture, Italy. 2 Surgical Oncology Unit, IRCCS-CROB, Rionero in Vulture, Italy. 3 Radiology Unit, IRCCS-CROB, Rionero in Vulture, Italy. 4 Emergency Unit, IRCCS-CROB, Rionero in Vulture, Italy Purpose/Objective: Neoadjuvant chemoradiotherapy (nCRT) is the standard of care in locally advanced rectal cancer (LARC) improving local control and resectability with surgery scheduled after a gap of several weeks. However, the optimal waiting time from nCRT end to surgery to has not been established yet. Several studies are going on. We tested the impact of delayed surgery after 12 weeks from nCRT in comparison to early surgical resection after completion of nCRT in a retrospective matched paired control study group. Material/Methods: Patients with LARC in our institution between 2022-24 wtih nCRT followed by surgery were retrospectively collected. Primary endpoints were tumor regression rate (TRG), downstaging (DWS), complete patological response (cPR).