Effect of Preoperative Inflammatory Diet on Clinical and Oncologic Outcomes Following Colorectal Cancer Surgery

<b>Objectives:</b> The dietary inflammatory index (DII), a validated tool for assessing the inflammatory potential of diet, has been widely identified as a significant risk factor for colorectal cancer (CRC). However, its role as a prognostic factor for CRC remains unexplored. This study examined the impact of preoperative dietary inflammation on clinical and oncologic outcomes following CRC surgery. <b>Methods</b>: The study population consisted of 126 patients who had surgical procedures for CRC and completed a food frequency questionnaire (FFQ) preoperatively between January 2018 and June 2020. <b>Results</b>: An optimal DII cut-off value of 0.90182 was used to categorize patients into the high-DII (<i>n</i> = 28) and low-DII (<i>n</i> = 98) groups. The high-DII group exhibited an older age (71.5 vs. 67.0, <i>p</i> = 0.020) and a significantly higher complication risk within 30 days postoperatively than the low-DII group (57.1% vs. 35.7%, <i>p</i> = 0.042). Other perioperative clinical outcomes did not demonstrate any significant differences between the two groups. The 5-year overall survival (OS) rates were 90.4% and 41.3% in the low-DII and high-DII groups, respectively, in univariate survival analysis (<i>p</i> = 0.044). However, no statistical difference was observed in the disease-free survival (DFS) rate. In the multivariate survival analysis, low-DII (hazard ratio [HR]: 0.118; 95% confidence interval [CI]: 0.023-0.613, <i>p</i> = 0.011) and M1 stage (HR: 10.910; 95% CI: 1.491-79.847, <i>p</i> = 0.019) were identified as independent prognostic factors for OS, while perineural invasion (HR: 3.495; 95% CI: 1.059-11.533, <i>p</i> = 0.040) served as an independent prognostic factor for DFS. <b>Conclusions:</b> A high preoperative DII score, indicative of an inflammatory dietary pattern, was correlated with increased postoperative complications and functioned as an independent prognostic indicator for OS.