Cancer Treat Res Commun. 2026 Jul 22;48:101326. doi: 10.1016/j.ctarc.2026.101326. Online ahead of print.
ABSTRACT
BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy with limited durable treatment options despite evolving multimodal and systemic strategies. Systemic inflammation has emerged as a clinically relevant determinant of outcomes in several cancers. The systemic immune-inflammation index (SII; platelet count x neutrophil count / lymphocyte count) integrates key circulating immune cell populations and may serve as an accessible prognostic biomarker in PDAC.
METHODS: A systematic search of PubMed was performed for studies published up to 11 April 2025. Eligible full-text English studies reported hazard ratios (HRs) with 95% confidence intervals (CIs) for overall survival (OS) according to SII (typically high versus low SII, defined by a study-specific cutoff). Pooled HRs were calculated using an inverse-variance random-effects model. Heterogeneity was assessed using Cochran’s Q and the I2 statistic. Small-study effects were evaluated by funnel plot inspection and Egger’s regression test.
RESULTS: Seventeen studies (18 datasets) comprising 4218 patients were included. Elevated SII was associated with worse OS (pooled HR 1.58, 95% CI 1.19 – 2.08; p < 0.01). Between-study heterogeneity was substantial (I2 = 89.9%). Funnel plot inspection did not suggest major asymmetry, and Egger’s test did not provide statistical evidence of small-study effects (p = 0.072).
CONCLUSIONS: Elevated SII is associated with poorer overall survival and represents a practical prognostic biomarker derived from routine laboratory testing. Considerable heterogeneity across studies-likely driven by differences in case mix, treatment context, and SII cutoff definitions-underscores the need for standardized thresholds and prospective, harmonized validation studies.
PMID:42485687 | DOI:10.1016/j.ctarc.2026.101326
