CARE: Protocol of a randomised trial evaluating the feasibility of preoperative intentional weight loss to support postoperative recovery in patients with excess weight and colorectal cancer.

Aim: Excess weight increases the risk of morbidity following colorectal cancer surgery. Weight loss may improve morbidity, but it is uncertain whether patients can follow an intensive weight loss intervention while waiting for surgery and there are concerns about muscle mass loss. The aim of this trial is to assess the feasibility of intentional weight loss in this setting and determine progression to a definitive trial.

Methods: CARE is a prospectively registered, multicentre, feasibility, parallel, randomised controlled trial with embedded evaluation and optimisation of the recruitment process. Participants with excess weight awaiting curative colorectal resection for cancer are randomised 1:1 to care as usual or a low-energy nutritionally-replete total diet replacement programme with weekly remote behavioural support by a dietitian. Progression criteria will be based on the recruitment, engagement, adherence, and retention rates. Data will be collected on the 30-day postoperative morbidity, the typical primary outcome of prehabilitation trials. Secondary outcomes will include, among others, length of hospital stay, health-related quality of life, and body composition. Qualitative interviews will be used to understand patients' experiences of and attitudes towards trial participation and intervention engagement and adherence.

Conclusion: CARE will evaluate the feasibility of intensive intentional weight loss as prehabilitation before colorectal cancer surgery. The results will determine the planning of a definitive trial.