Systemic Inflammation and Survival in Stage IV Colorectal Cancer: A Retrospective Cohort Study.

Background: In metastatic colorectal cancer (mCRC), systemic inflammation and routine laboratory parameters may reflect host-tumor interactions and provide additional prognostic information. This study evaluated the association between baseline clinicopathological and laboratory parameters, including the derived neutrophil-to-lymphocyte ratio (dNLR), and overall survival (OS) in patients with stage IV colorectal adenocarcinoma. Methods: We conducted a retrospective cohort study including 92 patients diagnosed with metastatic colorectal adenocarcinoma and treated at a single oncology center between February 2022 and December 2024. Baseline laboratory parameters were collected at diagnosis. Survival was analyzed using Kaplan-Meier estimates with log-rank testing. Prognostic associations were evaluated using univariable and multivariable Cox proportional hazards regression models adjusted for relevant clinical and treatment-related factors. Results: The cohort was predominantly male (62%) and younger than 70 years (66%), with 80 deaths recorded during follow-up. In univariable analyses, primary tumor resection, irinotecan-based first-line therapy, elevated AST, and dNLR tertiles were associated with OS. However, after multivariable adjustment, only irinotecan-based first-line therapy remained independently associated with poorer survival (HR 2.10, 95% CI 1.16-3.81; p = 0.022). Continuous dNLR, anemia (WHO sex-specific), and AST elevation did not retain independent prognostic significance. Conclusions: In this cohort of patients with mCRC, inflammation-related laboratory markers demonstrated associations with survival in unadjusted analyses but did not remain independent predictors after adjustment for clinical and treatment-related confounders. These findings highlight the importance of rigorous multivariable modeling when evaluating inflammatory biomarkers in metastatic colorectal cancer.