A scoping review of preoperative weight loss interventions on postoperative outcomes for patients with gastrointestinal cancer.

BACKGROUND: Obesity is associated with increased risk of surgical complications in some settings. OBJECTIVE: As a precursor to a systematic review, we conducted a scoping review of intentional preoperative weight loss to describe these interventions, their feasibility and effectiveness for patients with gastrointestinal cancer. METHODS: In April 2024, Ovid MEDLINE, EMBASE, CINAHL, and Google Scholar were searched for primary studies of intentional weight loss before elective gastrointestinal cancer surgery. Extracted data encompassed recruitment and attrition, intervention types, adherence, anthropometric and body composition changes, and surgical outcomes. Study quality was assessed using the Risk of Bias In Non-randomized Studies of Interventions tool. RESULTS: The search produced 7 articles (4 non-randomized clinical trials), which were all conducted in Japan, and involved 258 participants with a baseline BMI ≥25 kg/m2. Weight loss interventions included dietary modification (n = 3), exercise (n = 1), and combination (n = 3). None of the articles reported rates of recruitment, 2 adherence (97-100 %), and 4 reported attrition rates (0-18 %). All reported weight reductions of -1.3 to -6 kg and 4.5-6.9 % (n = 7), compared to baseline. Three of four non-randomized trials observed a reduction in postoperative complications, as compared to control; yet all trials were at critical risk of bias. CONCLUSION: Strong conclusions could not be made due to the limited reporting and critical risk of bias; further systematic review is not recommended at this time. To establish more robust evidence, there is a clear need for high-quality trials.