Diagnostic utility and discriminative ability of cholesterol-modified prognostic nutritional index and inflammatory indicators in colorectal cancer: a retrospective case-control study.

Malnutrition and altered biochemical parameters are common in colorectal cancer (CRC) patients. This study aimed to evaluate the diagnostic utility and discriminative ability of nutritional indices, including cholesterol-modified prognostic nutritional index (CPNI), prognostic nutritional index (PNI), nutritional risk index (NRI), and controlling nutritional status (CONUT) score in CRC. This retrospective case-control study included 100 CRC patients and 100 healthy controls. Baseline clinical and laboratory data were compared between the two groups to determine the capacity of these indices to distinguish CRC patients from healthy individuals. CRC patients demonstrated significantly lower nutritional markers (BMI, HDL, total protein, albumin, PNI, and NRI;  < 0.05) and markedly higher inflammatory/tumor-related parameters (CA-19.9, CEA, CRP, and CPNI;  < 0.001) compared to controls. Malnutrition prevalence, defined by CPNI, was significantly higher in the CRC group (54% vs. 10%,  < 0.001). ROC analysis identified CPNI as the most effective diagnostic discriminator (AUC = 0.804), followed by NRI (AUC = 0.756) and PNI (AUC = 0.728). Multivariate analysis revealed that elevated CPNI (OR = 2.339) and PNI (OR = 3.386) were independent indicators of CRC presence. No indices significantly correlated with tumor localization, size, or lymph node involvement, suggesting they reflect systemic status rather than local tumor burden. CPNI, PNI, and NRI demonstrated strong diagnostic performance in distinguishing CRC patients from healthy controls and appear to reflect systemic nutritional and inflammatory status at the time of diagnosis. In contrast, the CONUT score showed limited clinical utility, and none of the indices were associated with tumor size, location, or lymph node metastasis in this cross-sectional cohort. While these markers are effective diagnostic indicators, prospective longitudinal studies are required to validate their actual prognostic value regarding survival and recurrence.