High Cancer Inflammation Prognostic Index Identifies Patients With Stage II Colorectal Cancer With Outcomes Comparable to Stage III

Background: Risk stratification after curative resection remains challenging in stage II-III colorectal cancer (CRC). The cancer inflammation prognostic index (CIPI) has been proposed as a novel prognostic marker; however, whether high-risk stage II disease, as defined by CIPI, has outcomes comparable to those of stage III CRC remains unclear, particularly in patients with normal carbohydrate antigen 19-9 (CA19-9) levels. Patients and Methods: We retrospectively analyzed 654 patients with pathological stage II-III CRC and normal preoperative CA19-9 who underwent curative resection between 2008 and 2018. Patients were stratified using a validated CIPI cutoff (56.9). Disease-free (DFS) and overall (OS) survival were evaluated using Kaplan–Meier analysis and Cox proportional hazards models. Results: A high CIPI was significantly associated with poor DFS and OS (both log-rank p<0.01). In multivariate analysis, CIPI ≥56.9 independently predicted worse DFS (hazard ratio=1.91, 95% confidence interval=1.25-2.91; p<0.01) and OS (hazard ratio=2.57, 95% confidence interval=1.42-4.64; p<0.01). Among patients with stage II disease, those with a high CIPI demonstrated DFS and OS comparable to those with stage III CRC (DFS: p=0.31; OS: p=0.49). Conclusion: CIPI identifies biologically high-risk stage II CRC with long-term outcomes comparable to stage III disease among patients with normal CA19-9 levels, supporting its role as a complementary prognostic tool beyond conventional pathological staging.