SIRI as a Prognostic Marker in Metastatic Pancreatic Cancer

<i>Background and Objectives:</i> 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. <i>Materials and Methods:</i> 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. <i>Results</i>: The median OS and PFS were 7 and 4 months, respectively. Multivariate analysis revealed that ECOG ≥ 2 (HR: 2.094, <i>p</i> = 0.019), liver metastasis (HR: 2.039, <i>p</i> = 0.027), and each unit increase in SIRI (HR: 1.156, <i>p</i> < 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, <i>p</i> = 0.019). <i>Conclusions</i>: 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.