Preoperative Weight Loss Is Feasible, Safe, and Cost-Effective for Colorectal Cancer

A structured preoperative weight loss program is both feasible and safe for adults awaiting colorectal cancer (CRC) surgery, a recent UK-based study finds. Participants following a low-energy, high-protein diet lost a median of 6.1 kg before surgery without serious adverse events, maintained muscle mass, and saw improvements in postoperative symptoms such as fecal incontinence and skin issues.

Early modeling suggests the approach may also be cost-effective, supporting its potential for broader clinical use.

This randomized clinical trial is published in JAMA Network Open.

“In this randomized clinical trial, an intensive weight loss intervention was feasible and safe for patients with excess weight awaiting colorectal cancer resection,” wrote the researchers of the study. “Compared with usual care, intervention participants lost weight without compromising their fat-free mass and had fewer symptoms affecting life after surgery.”

Preoperative weight loss in patients with CRC is a complex issue, as both excess weight and unintended weight loss can impact surgical outcomes.² Previous research showed that losing 3% or greater of body weight in the 6 months before surgery was significantly associated with delayed recovery and higher 60-day readmission rates, highlighting the risks of malnutrition.

The CARE study was an assessor-blinded, randomized clinical trial conducted from March 2023 to August 2024 at 8 hospitals across England.¹ Adults with a body mass index (BMI) of 28 or higher who were scheduled for elective, curative CRC surgery were eligible. Participants were randomized to receive either standard care or a preoperative low-energy total diet replacement program, providing 800 kcal/day and 76 g/day of protein, with dietetic support delivered via telephone.

Primary feasibility outcomes included recruitment, engagement with dietetic calls, adherence to weight loss targets, and retention. Secondary outcomes assessed morbidity, postoperative symptoms, and changes in weight and fat-free mass, with longer-term health and cost-effectiveness modeled over a 30-year horizon using cohort simulation.

Of the 150 patients approached, 71 were randomized (36 to the intervention, 35 to usual care), with a mean (SD) age of 64 (8.7) years and mean BMI of 35.4. Intervention participants attended 85% of dietetic calls, and 61% achieved 5% or greater weight loss before surgery compared with 9% in the usual care group (OR, 16.8; 95% CI, 4.3-65.3). On average, intervention participants lost 6.1 kg (SD, 3.0), which was 4.3 kg more than the usual care group (95% CI, 2.7-5.8 kg), with negligible change in fat-free mass (0.1 kg; 95% CI, −3.9 to 4.0 kg). There was no significant difference in overall postoperative complications (39% vs 40%). However, fecal incontinence improved by −8.6 points (95% CI, −16.7 to −0.5) and sore skin by −15.9 points (95% CI, −25.3 to −6.6) in the intervention group. Furthermore, exploratory analysis suggested that participants losing 3.2% or greater of their body weight had a 50% relative reduction in complications (95% CI, 1% to 78%), and cost-effectiveness modeling favored the intervention.

However, the researchers acknowledged several limitations. Usual care participants lost around 2 kg preoperatively, likely due to trial engagement, and participants were generally fitter than population cohorts. Additionally, weekly dietitian contact may have increased minor adverse event reporting. Therefore, the researchers noted that future trials should include frailer patients and use more sensitive end points, such as the Comprehensive Complication Index.

Despite these limitations, the researchers believe the study demonstrates that a preoperative low-energy total diet replacement program before CRC surgery is feasible, safe, and well tolerated, achieving significant weight loss without compromising muscle mass.

“An intensive preoperative weight loss intervention was safe, feasible, and likely cost-effective as part of prehabilitation before colorectal cancer surgery with evidence of improvements in key symptoms,” wrote the researchers.

References

1. Koutoukidis DA, Jebb SA, Reynolds S, et al. Preoperative weight loss in patients with excess weight and colorectal cancer: the CARE feasibility randomized clinical trial. JAMA Netw Open. 2025;8(12):e2547126. doi:10.1001/jamanetworkopen.2025.47126

2. Joshi UM, Ratz D, Frankel TL, et al. Longitudinal dynamic in weight loss impacts clinical outcomes for veterans undergoing curative surgery for colorectal cancer. Fed Pract. 2023;40(suppl 1):S24-S33. doi:10.12788/fp.0377