Effect of immunonutrition on postoperative infectious complications and survival after colon cancer surgery: long-term follow up of randomized clinical trial.

BACKGROUND: A previous randomized clinical trial (RCT) in patients undergoing elective colon cancer surgery showed that preoperative immunonutrition did not reduce short-term postoperative infectious complications. This study reports the long-term follow-up of that RCT, evaluating the impact of preoperative immunonutrition and the association of postoperative infectious complications with survival outcomes. METHODS: This secondary analysis used prospectively collected survival data from a prior RCT in which patients were randomized 1:1 to receive either preoperative immunonutrition plus a normal diet or a normal diet alone (control) for 7 days before surgery. The primary endpoints were disease-free survival (DFS) and overall survival (OS). Survival outcomes were analysed in relation to randomized treatment allocation and clinicopathological variables, including postoperative complications, using Kaplan-Meier methods and Cox proportional hazards models. RESULTS: A total of 161 patients were included, with 79 randomized to immunonutrition and 82 to control. The mean age was 65.3 years, and 65.8% were male, with similar baseline characteristics between groups. After a median follow-up of 57 months (range 4-65), preoperative immunonutrition did not affect 5-year DFS (80% versus 86% in controls; P = 0.474) or 5-year OS (88% versus 90%; P = 0.761). In contrast, postoperative infectious complications were associated with lower 5-year OS (74% versus 92%; P = 0.013) and showed a trend towards worse DFS (71% versus 86%; P = 0.065). On multivariable analysis, advanced T category and postoperative infectious complications remained independently associated with poorer DFS (HR 2.53; P = 0.041) and OS (HR 4.14; P = 0.007). The adverse prognostic effect of infectious complications was evident primarily in patients with advanced T category disease. CONCLUSION: Preoperative immunonutrition did not improve long-term survival after colon cancer surgery. Postoperative infectious complications were independently associated with worse long-term outcomes, providing prospective evidence that supports previous observational findings.