SIRI as a Prognostic Marker in Metastatic Pancreatic Cancer.

Background and Objectives: Systemic inflammation plays a critical role in cancer progression and prognosis. The Systemic Inflammation Response Index (SIRI), a novel marker integrating neutrophil, monocyte, and lymphocyte counts, has been suggested as a prognostic indicator in various malignancies. This study aimed to evaluate the prognostic significance of SIRI in patients with metastatic pancreatic cancer receiving first-line chemotherapy. Materials and Methods: This retrospective study included 147 patients with metastatic pancreatic cancer who received first-line chemotherapy or best supportive care between 2010 and 2024. Clinical and laboratory data were collected from medical records. Overall survival (OS) and progression-free survival (PFS) were assessed using the Kaplan-Meier method, and prognostic factors were identified by univariate and multivariate Cox regression analyses. Results: The median OS and PFS were 7 and 4 months, respectively. Multivariate analysis revealed that ECOG ≥ 2 (HR: 2.094, p = 0.019), liver metastasis (HR: 2.039, p = 0.027), and each unit increase in SIRI (HR: 1.156, p < 0.001) were independent predictors of poorer OS. Patients with SIRI > 1.86 had significantly shorter OS compared to those with SIRI ≤ 1.86 (median OS: 4 vs. 9 months, p = 0.019). Conclusions: SIRI is an independent prognostic marker for survival in metastatic pancreatic cancer patients undergoing first-line and subsequent lines of chemotherapy. These inflammation-based markers are simple, cost-effective tools that could be integrated into routine clinical practice to aid in risk assessment and treatment planning.