TPS271 Background: Locally advanced colorectal cancer (LACRC) is recommended to receive neoadjuvant chemotherapy(NCT) by the NCCN guidelines before surgery. NCT might reduce tumor size, achieve downstaging of the tumor and lymph nodes, improve R0 resection rate, enhance prognosis or even watch-and-wait. Previous studies have shown a 2.07% retrieval rate of lymph nodes beyond 5 cm along the bowel for cases classified as T≤3, with an even lower incidence of positive lymph nodes. Retrospective cohort comparison at our center showed that reducing the extent of bowel resection (3 cm of distal margin and 5 cm of proximal margin) after NCT did not affect the lymph node retrieval and the 1-year DFS. Extending the resection length of the bowel or expanding the scope of regional mesenteric lymph node dissection beyond 5 cm does not improve staging accuracy. Instead, it might increase the risk of complications . For LACRC with ycT≤3N0M0 (stage IIA or lower) after NCT, the optimal extent of bowel resection remains a subject for further investigation. Methods: This is a prospective, multicenter, randomized phase III-controlled trial conducted in collaboration with the Sixth Affiliated Hospital of Sun Yat-sen University and multiple domestic colorectal cancer centers. Patients with upper rectal or rectosigmoid junction tumors at a clinical stage of cT3-4N+M0 will be enrolled. For patients with pMMR/MSS status: Tumor downstaged to T≤3N0M0 after NCT or total neoadjuvant therapy (TNT). Chemotherapy regimens include, but are not limited to, FOLFOX6, CAPOX, or FOLFOXIRI. For patients with dMMR/MSI-H: Tumor downstaged to T≤3N0M0 after immunotherapy. The trial will compare conventional resection margins with reduced margins in patients who have met the ycT ≤3N0M0 regression criteria following NCT or TNT. Reduced resection margins refer to the surgical resection region including 5 cm bowel proximal to the tumor, 3 cm bowel distal to the tumor and lymph node dissection in the corresponding mesentery. Conventional resection margins refer to the surgical resection region including 10 cm bowel proximal to the tumor, 5 cm bowel distal to the tumor, and lymph node dissection in the corresponding mesentery. The goal of this clinical trial is to learn evaluate the safety and efficacy of reduced surgical resection margins in patients with ycT≤3N0M0 regression following NCT. The primary research objective is 3-year disease-free survival (DFS). The secondary research objectives include R0 resection rate, number of lymph nodes dissected, surgical safety metrics and other survival outcomes. This study plans to enroll 874 patients, with 10 patients enrolled as of August 30th, 2025. Registration with ClinicalTrials.gov (NCT 07038122) has been completed. Clinical trial information: NCT 07038122 .
Liu et al. (Sat,) studied this question.