Effect of Total Mesorectal Excision (TME) quality on 3-year overall survival in low rectal cancer based on the LASRE trial

High-level evidence on the long-term efficacy of postoperative TME quality in patients with low rectal cancer is lacking. The LASRE trial was used as background data to further explore the impact of TME quality on overall survival. We carried out a secondary analysis of the LASRE trial, which prospectively enrolled patients less than 5 cm from the dentate line from 22 hospitals in China who had undergone total mesorectal resection. TME quality was classified into 3 grades: grade A (complete), grade B (nearly complete), and grade C (incomplete), which were independently judged by the pathologist and surgeon, respectively, and if the results were inconsistent, then a third party finalized the grading based on photos of the specimen. 921 patients were included in the analysis, 787 (85.5%) in grade A, 108 (11.7%) in grade B, and 26 (2.8%) in grade C. The median follow-up was 36.0 months, and Kaplan-Meier curves showed that 3-year OS before PSM matching was 93.2% for grade A, 84.3% for grade B, 88.5% for grade C (P=0.0038), and 85.1% for grade B/C (P=0.0011). After PSM, it was 92.5% for grade A and 86.8% for grade B/C (P=0.044). TME quality was an independent influence on overall survival before PSM matching (HR=1.691, 95% CI: 1.133~2.522, p=0.010), and after PSM matching, TME quality remained an independent factor for OS (HR=1.881, 95% CI: 1.035~3.416, p=0.038). Excellent TME quality after surgery for low rectal cancer contributes to an improved prognosis and is an independent factor influencing long-term outcome.