Unveiling the impact of body mass index on surgical difficulty and oncological prognosis in low rectal cancer: post-hoc analysis of the LASRE trial.

Purpose: This post-hoc analysis of the LASRE trial aims to evaluate the impact of body mass index (BMI) on surgical difficulty and oncological outcomes in patients undergoing laparoscopic or open resection for low rectal cancer.

Methods: The LASRE trial was a multicenter, randomized controlled trial comparing laparoscopic and open surgery for low rectal cancer. Patients aged 18-75 years with rectal adenocarcinoma located within 5 cm of the dentate line were enrolled and stratified into four BMI groups: underweight (BMI < 18.5 kg/m²), normal weight (BMI 18.5-23.9 kg/m²), overweight (BMI 23.9-27.9 kg/m²), and obese (BMI ≥ 28.0 kg/m²). The primary endpoints were surgical difficulty, circumferential resection margin (CRM) positivity, and postoperative complications.

Results: A total of 1,039 patients were included. Obese patients exhibited significantly longer operative times (P < 0.001) and higher intraoperative blood loss (P = 0.001). The 30-day complication rate (P = 0.030) and Clavien-Dindo classification (P = 0.040) differed significantly between groups. However, CRM positivity rates did not significantly differ between BMI groups (P = 0.42). During the median follow-up of 36 months, the 3-year OS rate was comparable across BMI groups (P = 0.709), and the 3-year DFS rate showed no significant differences among the BMI groups (P = 0.966).

Conclusions: Higher BMI increases surgical difficulty and postoperative complications in low rectal cancer but does not significantly impact CRM positivity or DFS. These findings underscore the importance of considering BMI in surgical planning and patient counseling.