Prognostic Value of the Cancer Inflammation Prognostic Index (CIPI) in De Novo Metastatic Colon Cancer: A Multicenter Retrospective Cohort Study.

IntroductionThe Cancer Inflammation Prognostic Index (CIPI) is a composite biomarker that integrates carcinoembryonic antigen (CEA), neutrophil, and lymphocyte counts to reflect both tumor burden and systemic inflammation. Although CIPI has demonstrated prognostic value in early-stage and previously treated metastatic colorectal cancer, its role in untreated, de novo metastatic colon cancer remains unclear.MethodsThis multicenter, retrospective cohort study included 287 patients diagnosed with de novo metastatic colon cancer between 2010 and 2023. CIPI was calculated by multiplying serum CEA by the neutrophil-to-lymphocyte ratio, and the optimal cutoff value for overall survival (OS) was determined using receiver operating characteristic (ROC) curve analysis. Patients were stratified into low- and high-CIPI groups based on this threshold.ResultsThe median follow-up period was 4.0 years, during which 202 patients (70.4%) died. The optimal CIPI cutoff value for OS was 86.09. Median OS was significantly shorter in the high-CIPI group compared with the low-CIPI group (36.0 vs 14.5 months, p < 0.001). In multivariable Cox regression analysis, a high CIPI remained an independent prognostic factor for OS (hazard ratio, 2.29; 95% confidence interval, 1.65-3.17; p < 0.001). In a separate multivariable model, elevated CEA was also independently associated with poorer overall survival.ConclusionCIPI independently predicts overall survival in patients with de novo metastatic colon cancer. Its simplicity, cost-effectiveness, and derivation from routine laboratory data make it a practical and promising tool for baseline risk stratification and individualized follow-up planning.