ESTRO 2025 - Abstract Book

S1245

Clinical – Lower GI

ESTRO 2025

Keywords: watch-and-wait, risk stratification, follow-up

3523

Digital Poster Prospective trial of organ preservation in patients with rectal cancer: preliminary outcomes in our center. Esther Agudo Rey, Juan B Quirós Rivero, Victoria Vera Barragán, Patricia Ruiz Leal, María Medina Cobacho, María C Fernández Alcala, Carmen Corral Fernández, Joaquín J CabreraRodríguez, María F Ropero Carmona, Yésika Rios Kavadoy Radiation Oncology, University Hospital of Badajoz, Badajoz, Spain Purpose/Objective: Preliminary outcomes of patients diagnosed with rectal cancer included in a treatment protocol with total neoadjuvant therapy (TNT) and multimodal prehabilitation with organ preservation “Watch & Wait” (W&W) in those who achieve a complete clinical response. Material/Methods: Prospective trial of 40 pts, I (7.5%), II (15%), III (77,5%) clinical stage treated from January 2023 to October 2024. The median age was 66 years old (range 44-84); 77.5% males. Middle rectum was the most frequent location (62,5%). Involved mesorectal fascia 35%. Extramural vascular invasion 17.5%. CEA>10 22.5%. Mucinoso 7.5%. Extramesorectal nodes 10%. TNT with radiotherapy using VMAT-IGRT with a simultaneous integrated boost (45Gy pelvis/54Gy primary tumor/25 fractions) with capecitabina concurrent. Followed by 6 cycles de chemotherapy (folfox 87.5%). Nutritional and physical prehabilitation was carried out. Patients with clinical complete response (CCR) after TNT were offered W&W. Results: Of the 40 patients included, 27 have completed the reevaluation. The median follow-up was 15.52 months. The median time between the end of radiotherapy and the reassessment MRI was 16.85 weeks. 48.1% CRC, 29.6% near complete response and 22.2% incomplete clinical response. 59.3% begin W&W without any tumor regrowth and free of stomata. Patients underwent surgery (33.3% abdominoperineal amputation) one patient had a complete pathological response and none have relapsed. The treatment was well tolerated without grade III-IV adverse effects. Conclusion: Preliminary results show a high percentage of RCC and organ preservation with excellent tolerance to the proposed treatment scheme. It is necessary to include more patients with a longer follow-up to obtain conclusive results.

Keywords: Organ preservation, Rectal cancer, TNT.