Development and Validation of a Novel Composite Indicator SIRI_HDL_ALB for Prognostic Prediction in Patients with Distal Cholangiocarcinoma After Radical Resection.

BACKGROUND: Distal cholangiocarcinoma (dCCA) carries a poor prognosis even after radical resection. Systemic inflammation, lipid metabolism, and nutritional status are all involved in tumor progression, but a biomarker integrating these three dimensions is lacking. This study aimed to develop and validate a novel composite indicator integrating the systemic inflammatory response index, high-density lipoprotein cholesterol, and albumin (SIRI_HDL_ALB), and evaluate its prognostic value in dCCA patients after pancreaticoduodenectomy. MATERIALS AND METHODS: 230 dCCA patients who underwent radical resection (2011-2024) were retrospectively enrolled. SIRI_HDL_ALB was calculated as (neutrophils × monocytes/lymphocytes)/(HDL cholesterol × albumin). Time‑dependent ROC, Kaplan-Meier, Cox regression, restricted cubic spline (RCS), competing risk analysis, and subgroup analyses were performed. A nomogram incorporating SIRI_HDL_ALB was constructed and internally validated by bootstrap (1000 iterations). RESULTS: For descriptive baseline comparisons and Kaplan-Meier visualization only, an exploratory 36-month OS-derived cut-off value of 0.143 was applied, resulting in a low-score group (n=28) and a high-score group (n=202). The high-score group had significantly worse OS and RFS than the low-score group (both log-rank P<0.01). In all subsequent Cox regression, restricted cubic spline, nomogram construction, and model-performance analyses, SIRI_HDL_ALB was analyzed as a continuous variable. Higher SIRI_HDL_ALB remained independently associated with OS (HR=1.858, 95% CI: 1.095-3.155, P=0.022) and RFS (HR=1.700, 95% CI: 1.014-2.849, P=0.044). Adding SIRI_HDL_ALB to the clinicopathological model provided modest incremental discrimination, with corrected C-index values of 0.720 for OS and 0.737 for RFS. CONCLUSION: SIRI_HDL_ALB is an independent prognostic factor for OS and RFS in dCCA patients after radical resection. By integrating inflammation, lipid metabolism, and nutrition, it adds incremental value to traditional clinicopathological factors.