Association Between Vitamin D Deficiency, Malnutrition, and Systemic Inflammation in Advanced Colorectal Cancer: A Hospital-Based Cross-Sectional Study

Background/Objectives: Vitamin D deficiency and malnutrition may lead to poor outcomes in colorectal cancer (CRC) patients. This study aims to perform an integrative analysis of serum vitamin D, nutritional status, anthropometric parameters and biochemical profiles in advanced CRC patients. Methods: The study included 58 advanced CRC patients. Serum vitamin D levels were measured by a chemiluminescence immunoassay. Nutritional status was evaluated with the Mini Nutritional Assessment (MNA). Body composition profiles were assessed using a bioelectrical impedance analyzer, and handgrip strength was measured with a handgrip dynamometer. Biochemical and clinical parameters were retrieved from an electronic database. Correlation, regression and receiver operating characteristic (ROC) analyses were performed. Results: Abnormal nutritional status and vitamin D deficiency were diagnosed in 55.17% and 50.00% of patients, respectively. Sarcopenia was diagnosed in 29.31%. Serum vitamin D concentrations were negatively correlated with absolute neutrophil counts (ANC). MNA scores showed significant negative correlations with ANC, platelet count, alkaline phosphatase and carcinoembryonic antigen. In multivariable regression models, albumin remained statistically associated with both serum vitamin D levels (β 7.049; 95% CI: 1.686–12.413; p = 0.011) and MNA score (β 6.951; 95% CI: 4.623–9.278; p < 0.001). Furthermore, albumin showed exploratory performance in ROC analyses for malnutrition and vitamin D deficiency (AUCROC 0.814 and 0.725, respectively), which should be interpreted cautiously given potential overlap with MNA-defined nutritional status and the limited sample size. Conclusions: Vitamin D deficiency, malnutrition and systemic inflammation commonly co-occur and are closely interrelated in patients with advanced CRC. A comprehensive assessment of nutritional status in a CRC supportive care setting is recommended.