Tumor Marker Index Based on CEA and CA19-9 as a Prognostic Biomarker in Resectable Colon Cancer.

Background/Aim: Despite curative resection, the prognosis after surgery for colon cancer varies considerably even among patients within the same TNM stage. There is a need for reliable biomarkers to complement the TNM classification. In pancreatic cancer, tumor markers have been reported as indicators of biological resectability. We therefore focused on tumor markers in colon cancer and investigated the prognostic significance of the tumor marker index (TMI). Patients and Methods: We retrospectively reviewed patients with colon cancer (cecum to rectosigmoid) who underwent curative resection at our institution between 2011 and 2023. Among them, 361 patients without missing clinical or laboratory data were included. TMI was defined as the product of preoperative serum carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) levels. Patients were stratified into low- and high-TMI groups based on cutoff values determined by receiver operating characteristic (ROC) curve analysis with recurrence as the outcome. Three-year recurrence-free survival (3y-RFS), local recurrence-free survival (3y-LRFS), and distant metastasis-free survival (3y-DMFS) were compared between groups. Results: =0.103). Conclusion: TMI was associated with postoperative recurrence patterns in curatively resected colon cancer. TMI may serve as a simple and clinically useful biomarker to complement TNM staging and improve risk stratification after curative surgery.