ESTRO 2025 - Abstract Book

S1271

Clinical – Lower GI

ESTRO 2025

4111

Digital Poster WATCH AND WAIT PROTOCOL IN RECTAL CANCER: FIRST RESULTS IN A SINGLE CENTRE

Marta Pérez Cobos 1 , Ignacio Azinovic 1 , José Vara Santos 1 , Ignacio Navarro Ruiz de Adana 1 , Leticia Del Campo Rodríguez Ponga 1 , Patricia Salgado González 1 , José Luis Domínguez Tristancho 2 , Eva Ruiz Hispán 3 , Raquel Fuentes Mateos 3 , Héctor Guadalajara Labajo 2 , Jesús García-Foncillas 3 , Javier Luna Tirado 1 1 Radiation Oncology, Hospital Fundación Jiménez Díaz, Madrid, Spain. 2 General and Digestive Surgery, Hospital Fundación Jiménez Díaz, Madrid, Spain. 3 Medical Oncology, Hospital Fundación Jiménez Díaz, Madrid, Spain Purpose/Objective: Total neoadjuvant therapy (TNT) integrates chemotherapy and radiotherapy before surgical intervention, to maximize tumor downstaging and improves the rates of complete pathological response. We aime to evaluate oncological response, organ preservation and toxicities. Material/Methods: 91 patients were included in the watch and wait protocol between 2020 and 2023. 73p received treatment with long course radiotherapy. 61% were male. Median age 65 years. T4 12p, T3 54p, and T2 7p. N0 12p and N+ 61p. The tumor was located in the proximal rectum in 18p, middle rectum 28p, and distal rectum 27p; with a median distance from the tumor to the anal margin of 7cm. The median dose received was 53 Gy. Results: After re-evaluation 37p present tumor persistence. 6p present recurrence (local disease). 5p developed metastasis (2 liver, 3 lung). In 53.4% of the patients underwent surgical intervention: 21p low anterior resection, 6p abdominoperineal resection, 2p discharge colostomy, 9p transanal endoscopic microsurgery , 1 intersphincteric Hartmann. Tolerance: 5p presented acute gastrointestinal toxicity ≥ G3 (1p G4 proctitis requiring surgery). None presented acute genitourinary toxicity ≥ G3. 1p presented acute cutaneous toxicity G3 (abscess). 5p do not complete radiotherapy treatment. Conclusion: In our experience, surgery was avoided in 46.6%p and only 8p (20.5%) underwent non-conservative surgery. The treatment has an excellent tolerance with the most frequent degree of toxicity ≤G1. TNT has emerged as a promising approach in the management of locally advanced rectal cancer. This approach may facilitate sphincter-preserving surgeries and reduce treatment-related toxicity. References: Kasi A, Abbasi S, Handa S, Al-Rajabi R, Saeed A, Baranda J, et al. Total Neoadjuvant Therapy vs Standard Therapy in Locally Advanced Rectal Cancer: A Systematic Review and Meta-analysis. JAMA Netw Open. 16 de diciembre de 2020;3(12). Ludmir EB, Palta M, Willett CG, Czito BG. Total neoadjuvant therapy for rectal cancer: An emerging option. Vol. 123, Cancer. John Wiley and Sons Inc.; 2017. p. 1497-506. Sellés EG, Pieretti DG, Higuero PP, Del Portillo EG, Macías VM, Domínguez MM, et al. Total neoadjuvant therapy for locally advanced rectal cancer: a narrative review. Future Oncol. agosto de 2023;19(25):1753-68. Keywords: total neoadjuvant therapy, rectal cancer