Efficacy of preoperative immunonutrition in malnourished patients undergoing colorectal cancer surgery: a study protocol for a multicenter randomized clinical trial

Background: Malnutrition is a significant risk factor for postoperative complications in patients undergoing colorectal cancer surgery. Although current guidelines recommend preoperative immunonutrition for malnourished patients, its clinical benefit remains controversial. Our previous randomized clinical trial assessing immunonutrition in unselected colon cancer patients showed no reduction in infectious complications. This study aims to evaluate the efficacy of preoperative immunonutrition in reducing postoperative complications in malnourished patients undergoing colorectal cancer surgery. Methods: This multicenter, parallel, superiority, randomized clinical trial will include patients with primary colorectal cancer and Nutritional Risk Screening (NRS) 2002 score of 3–5 from eight participating institutions. Patients will be randomly assigned (1:1) to receive either preoperative immunonutrition with oral nutritional supplements (400 mL/day) containing arginine and ω-3 fatty acids for 7 days before surgery (intervention group) or a standard preoperative diet alone (control group). The primary endpoint is the rate of infectious complications within 30 days postoperatively. Secondary endpoints include overall postoperative complication rate, length of hospital stay, perioperative body weight changes, and alterations in nutritional and immune response markers (serum transferrin, prealbumin, albumin, cytokines, prostaglandin E2, high-sensitivity C-reactive protein). A sample size of 176 patients (88 per arm) was determined to detect a significant reduction in infectious complications from 30% (control) to 12% (intervention), with 80% power and a two-sided α of 0.05. Discussion: This study addresses a critical gap in evidence by focusing on nutritionally at-risk colorectal cancer patients. Unlike previous trials on unselected populations, this trial specifically evaluates the impact of immunonutrition in a high-risk group in which nutritional optimization may yield clinical benefits. Additionally, the multicenter design enhances generalizability. If preoperative immunonutrition effectively reduces postoperative complications, it could support a targeted nutritional intervention strategy for malnourished colorectal cancer patients, optimizing perioperative care and potentially reducing the healthcare burden. Trial registration: Clinical Research Information Service KCT0008382. Registered on April 25, 2023.