Merve TURAN, Mehmet Nuri BAŞER
Acta Haematologica Oncologica Turcica - 2026;59(2):138-147
Aim: To evaluate the combined prognostic value of carcinoembryonic antigen (CEA) and the prognostic nutritional index (PNI) for overall survival (OS) and progression-free survival (PFS) in de novo stage IV colon cancer, and to compare their performance at baseline and at the first response assessment during treatment. Methods: This single-center retrospective study included 102 patients with de novo stage IV colon cancer who were diagnosed between 2018 and 2025. CEA and PNI were measured at baseline (T0) and at the first response assessment (T1). CEA cut-offs were derived by receiver operating characteristic analysis, and a literature-based PNI cut-off of 48.0 was applied. Patients were classified into four CEA/PNI groups. Survival was analyzed by Kaplan-Meier and Cox regression methods, with p<0.05 considered significant. Results: Median OS was 33.0 months, and median PFS was 12.4 months. At baseline, the highest-risk group (high CEA, low PNI) had shorter OS than the reference group (21.6 vs. 37.6 months, p=0.01) and was an independent predictor of death [hazard ratio (HR): 2.76, 95% confidence interval: 1.18-6.44, p=0.02]. The score was more discriminative at T1, where OS ranged from 19.8 to 60.6 months across groups (p=0.001). Bone metastasis (HR: 3.19) and absence of primary tumor surgery were the other independent predictors of poor OS. For PFS, left-sided location and surgery were independent favorable factors. Conclusion: The combined CEA/PNI score identifies a high-risk subgroup in de novo stage IV colon cancer using routine laboratory data. Its prognostic value was greatest when measured early in treatment, supporting serial assessments over a single baseline measurement.
