ESTRO 2025 - Abstract Book

S1208

Clinical – Lower GI

ESTRO 2025

Conclusion: Total neo-adjuvant treatment in locally advanced rectal cancer using MRI-guided integrated boost on the GTV resulted in limited local (8%) and distant relapse (12%). The high rate of persistent clinical and pathological complete response (44%) compares favorably to other published data using short course radiotherapy in TNT. This opens an avenue for rectum preserving strategies. Increased cCR and pCR could address the concern of increased loco regional recurrence observed in RAPIDO. However, long-term follow-up and prospective validation is needed.

Keywords: MRI guided radiotherapy, rectal cancer, SCRT

References: (1) Bahadoer RR, Dijkstra EA, van Etten B, et al.; RAPIDO collaborative investigators. Short-course radiotherapy followed by chemotherapy before total mesorectal excision (TME) versus preoperative chemoradiotherapy, TME, and optional adjuvant chemotherapy in locally advanced rectal cancer (RAPIDO): a randomised, open-label, phase 3 trial. Lancet Oncol. 2021 Jan;22(1):29-42. (2) Dijkstra EA, Nilsson PJ, Hospers GAP, et al.; Collaborative Investigators. Locoregional Failure During and After Short-course Radiotherapy Followed by Chemotherapy and Surgery Compared With Long-course Chemoradiotherapy and Surgery: A 5-Year Follow-up of the RAPIDO Trial. Ann Surg. 2023 Oct 1;278(4):e766-e772.