S689
Clinical – Lower GI
ESTRO 2026
Conclusion: Our results compare favourably to the RAPIDO study, although the pCR rate was lower than expected. This study adds to the growing real-world evidence supporting the effectiveness of the RAPIDO TNT regimen for LARC. References: 1) Bahadoer RR, et al. 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;22(1):29-42. 2) Dijkstra EA, et al. 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;278(4):e766-e772. Keywords: rectal cancer, RAPIDO, total neoadjuvant therapy Hypofractionated radiotherapy combined with immunotherapy and chemotherapy for locally recurrent rectal cancer: a prospective, phase II trial JUEFENG WAN, Ruiyan Wu, FAN XIA, ZHEN ZHANG Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China Purpose/Objective: Local recurrence of rectal cancer (LRRC) remains a therapeutic challenge. This study aimed to assess the outcome of hypofractionated radiotherapy(HFRT) with PD-1 inhibitor and chemotherapyin proficient mismatch repair or microsatellite stable (pMMR/MSS) patients with LRRC. Material/Methods: We conducted a prospective, single-arm, two-cohort, phase 2 trial enrolling LRRC patients with or without oligometastases. Eligible patients with previously untreated (cohort A) or progressive disease afterfirst line therapy (cohort B),were Proffered Paper 880 assigned received 25-40 Gy/5 Fx irradiation or 15-30 Gy/5 Fx reirradiation for pelvic recurrence,followdd by 18 weeks of chemotherapy, toripalimab, and stereotactic ablative radiotherapy (SABR) for all metastatic lesions between chemoimmunotherapy cycles. The primary endpoint was confirmedlocal recurrence objective response rate (ORR). The study is registered with ClinicalTrials.gov, NCT05628038. Results:
patients had cT3/4 (95%) and N1/2 disease (81%). Most patients had low (27%) and mid (61%) rectal tumours. Pre-treatment CRM involvement and EMVI were found in 74% and 48%, respectively. Three (2.6%) patients had dMMR disease. All patients completed 5 fractions of SCRT. Primary tumour boost (4-6Gy/2-3 fractions) were given in 26 (22%) patients. Median number of chemotherapy cycles received were 6 (XELOX, range 2- 8) and 9 (FOLFOX, range 9-9). However, only 90/117 (77%) completed all the neoadjuvant chemotherapy. Eight (6.8%) patients did not proceed to surgery due to progressive disease (n=6), medically unfit (n=1) and patient refusal (n=1). Median follow-up for all patients was 3.0 years (95% CI 2.7-3.4). Median interval between end of chemotherapy and surgery was 54 days (IQR 45-69). R0 and R1 resections were achieved in 101/109 (93%) and 8/109 (7%), respectively. Nine (8.3%) patients had pCR. TME was intact in 88% of resected specimens. Local, locoregional and distant recurrences were detected in 9/109 (8.3%) and 12/109 (11%) and 32/117 (27%), respectively. 2-year LRFS, LRRFS, DFS and OS were 96.2% (95% CI 90.2 – 98.6), 94.2% (95% CI 87.5 – 97.4), 73.2% (95% CI 63.9 – 80.5) and 92.8% (86.2 – 96.4), respectively.
BetweenJan31, 2023, and Jun 13, 2025, We enrolled 92 patients: 53 in cohort A and
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