SP6.15 Pre-operative intentional weight loss is safe, feasible, and preserves fat-free mass in patients with excess weight undergoing colorectal cancer surgery: a multi-centre randomised controlled trial

Abstract Aims Excess weight increases morbidity risk after colorectal cancer surgery. Pre-operative weight loss may reduce morbidity. We tested the feasibility of a weight loss intervention. Methods Adults with BMI≥28kg/m2 awaiting curative elective colorectal cancer resection from 9 centres across England were randomised 1:1 to receive usual care or dietetic support with a low-energy (800kcal/day, 76g protein/day) total diet replacement programme between decision to treat and surgery (ISRCTN39207707, prospectively registered). Progression criteria to a definitive trial included recruitment (≥72 patients), engagement (≥75% of dietetic phone calls attended), adherence (≥60% of intervention participants achieving ≥5% weight loss), and retention (≥85% at 30 days post-operatively). Secondary outcomes included changes in weight and fat-free mass. Results Between 27/03/2023-13/08/2024, seventy-five participants were randomised and 71 eligible participants undergoing surgery (n=36 intervention, n=35 usual care) were analysed [61% male, mean (SD) 64 (8.7) years, baseline BMI 35.4 (5.3) kg/m2, 87% with ASA score 2-3]. Participants attended 85% of their dietetic calls. The median (IQR) period from randomisation to surgery was 33 (25-43) days, during which 61% and 9% of intervention and usual care participants lost ≥5% of their weight, respectively [OR: 16.8 (95%CI: 4.3-65.3)]. Intervention participants lost 6.1kg (3.0) until surgery, which was an additional 4.3kg (95%CI: -5.8, -2.7) compared with usual care. Between-group adjusted change in fat-free mass was 0.1kg (95%CI: -3.9, 4.0). There were no intervention-related serious adverse events. Retention at 30 days post-operatively was 100%. Discussion The intervention was feasible without safety concerns meeting the progression criteria for a definitive trial.