Association of Systemic Inflammation Response Index With Long-Term Outcomes in Patients With Head and Neck Cancer Receiving Definitive Chemoradiation

PURPOSE Systemic inflammation is an important factor for carcinogenesis and tumor progression. Systemic Inflammation Response Index (SIRI) was suggested as one of the peripheral blood biomarkers to assess the magnitude of inflammation. Herein, we aimed to evaluate the prognostic value of SIRI in head and neck cancer. METHODS A single-institution database at a comprehensive cancer center was queried for patients with nonmetastatic head and neck cancer who underwent definitive chemoradiation between December 2011 and February 2024 with SIRI available for analysis. With the top quartile as a reference to evaluate high versus low SIRI, logistic multivariable analysis (MVA) was performed to identify variables associated with high SIRI. Cox MVA was performed to evaluate survival. Interaction term analysis was performed to evaluate whether there is a heterogeneous association of SIRI with outcomes stratified by p16 status. RESULTS A total of 638 patients met our criteria. The median follow-up was 45.9 months (95% CI, 44.4 to 47.7). Using the top quartile cutoff of 3.22 for SIRI, those who were male, underweight, had poor performance status, and had advanced T staging were more likely to have high SIRI, whereas those with other racial background, p16-positive, and larynx primary site were less likely to have high SIRI. Those with high SIRI had worse overall survival (OS; adjusted hazard ratio [aHR], 1.59 [95% CI, 1.15 to 2.25], P = .008), but not PFS (aHR, 1.18 [95% CI, 0.86 to 1.61], P = .320). Interaction term analysis did not reach statistical significance ( P interaction = .75 for OS, 0.84 for PFS). CONCLUSION Elevated SIRI was an independent, adverse prognostic factor for survival without heterogeneous association with outcomes based on p16 status. Further validation of SIRI would be warranted in future studies.