Preoperative Advanced Lung Cancer Inflammation Index as a Potential Marker for Incidental Gallbladder Carcinoma: A Matched Case–Control Study

Background and Objectives: Incidental gallbladder carcinoma (IGBC) is an uncommon but clinically significant finding after elective cholecystectomy, as failure to recognize malignancy preoperatively may lead to inadequate initial surgical management. Inflammation-based hematological indices have been explored in various gastrointestinal malignancies; however, data focusing on preoperative discrimination of IGBC are limited. This study aimed to evaluate the diagnostic performance of the Advanced Lung Cancer Inflammation Index (ALI) and other inflammatory and immunonutritional indices in distinguishing IGBC from benign gallbladder disease. Materials and Methods: This retrospective matched case–control study included patients who underwent elective cholecystectomy between 2020 and 2025. Nineteen patients with histopathologically confirmed IGBC were matched 1:4 by age and sex with 76 patients with benign gallbladder disease. Preoperative laboratory parameters obtained within 72 h before surgery were used to calculate inflammatory indices, including NLR, PLR, LMR, SII, CAR, ALI, and the CALLY index. Diagnostic performance was assessed using receiver operating characteristic (ROC) analysis. Independent associations with malignancy were evaluated using matched conditional logistic regression. Results: No significant differences were observed between benign and malignant groups in baseline demographic or routine laboratory parameters. Among derived indices, ALI and LMR demonstrated borderline differences, representing the closest discriminatory markers. In ROC analysis, ALI showed the highest diagnostic performance (AUC = 0.69), followed by LMR (AUC = 0.639). In matched conditional logistic regression, ALI was independently and inversely associated with malignancy (adjusted OR = 0.997 per unit, 95% CI: 0.9937–1.0000; p = 0.04); when rescaled per 100-unit increase, the adjusted OR was 0.93, whereas LMR did not reach statistical significance. Conclusions: Among evaluated preoperative inflammatory and immunonutritional indices, ALI demonstrated a more consistent association with incidental gallbladder carcinoma. Although its discriminative ability was moderate, ALI may serve as a complementary biomarker for preoperative risk stratification when integrated with clinical and radiological assessment.