Transanal endoscopic microsurgery vs. radical surgery for mid-low rectal cancer in patients with clinical complete or near-complete response after neoadjuvant chemoradiotherapy.

e15616 Background: Following neoadjuvant chemoradiotherapy (nCRT), total mesorectal excision surgery used to be the standard therapy for locally advanced rectal cancer (LARC). However, the radical surgery is associated with high complication rates and impairs patients' quality of life, especially for non-sphincter preservation procedures. For the past two decades, nCRT followed by organ preservation strategies like watch-and-wait (W&W) or local resection offers an alternative for patients being clinically evaluated with complete response or near complete response, however the oncological outcomes of these approaches require further exploration. Methods: We prospectively collected data on 80 patients with T3-4N0M0 or TanyN+M0 mid-low rectal cancer who achieved cCR or near-cCR after nCRT from May 2017 to September 2021 at 5 tertiary centers in China. Patients were divided into the TEM group (group A) or the radical surgery group (group B). Clinicopathological features, operative outcomes, oncological and functional results were analyzed. Results: A total of 76 cases were analyzed, with 38 in each group. Baseline characteristics were comparable between the two groups. Postoperative histology revealed 22 ypT0Nx(57.9%), 5 ypT1Nx(13.2%), 10 ypT2Nx (26.3%), 1 ypT3Nx(2.6%) in group A, and 18 ypT0N0 (47.4%), 5 ypT1N0 (13.2%), 11 ypT2-3N0 (28.9%), 1 ypT0N1 (2.6%), 3 ypT2-3N1 (7.9%) in group B. After a median follow-up of 61 months, 2 patients (5.26%) in group A experienced local recurrence, while none in group B. 8 patients (21.05%) in group A developed distant metastases compared to 5 (13.16%) in group B. There was no statistically significant difference between two groups in 5-year disease-free survival(P = 0.320), or 5-year overall survival (P = 0.425). Patients in group A had significantly faster postoperative recovery and a superior quality of life evaluated by the Wexner and LARS scores compared to group B. Conclusions: For cCR and near-cCR LARC patients after nCRT, organ preservation with TEM may serve as a staging method to evaluate local tumor persisrence. And it provides an alternative therapy for carefully selected patients who have needs to preserve sphincteric function or can’t tolerate radical resection, without significantly compensate long-term oncological outcomes. This strategy could relatively safely enable sphincteric function preservation for these patients with faster postoperative recovery and better quality of life. Clinical trial information: NCT03042000 .