Prognostic associations of systemic inflammation response index (SIRI) in patients with head and neck cancer: a systematic review and meta-analysis

Background/Objectives: Inflammation and immune evasion are linked to tumor progression. This cancer-related inflammatory response is reflected by a biomarker named the systemic inflammatory response (SIRI). SIRI is calculated by multiplying the peripheral blood neutrophil and monocyte counts and dividing by the lymphocyte count is a biomarker that has shown prognostic capacity in squamous cell head and neck cancer. We sought to perform a meta-analysis of SIRI data for head and neck cancer. Methods: A meta-analysis using a mixed-effects model was performed to estimate the overall effect size of prognostic capacity. The primary outcomes of interest were overall survival and progression-free survival, with effect sizes measured as log hazard ratios (HR). Results: Ten studies reporting data on overall survival revealed a pooled HR of 2.4 (p < 0.0001). This indicates higher SIRI patients are at greater risk of mortality relative to lower SIRI patients. Additionally, 3 studies reported metrics on progression-free survival, with a pooled HR of 2.32 (1.72, 3.13) (p < 0.0001). Minimal heterogeneity was observed for progression-free survival (I2 = 0%, p< 0.74). Conclusions: High SIRI portends worse overall survival. Since SIRI correlates to immune function and demonstrated minimal heterogeneity, these factors are among those most likely to be impacted by altered SIRI parameters.