Blood-Based Inflammatory Markers Are Associated with Treatment Outcomes in Head and Neck Squamous Cell Carcinoma Receiving Anti-PD-1 Therapy: CRP as a Superior Predictive Marker

Systemic inflammation is gaining increasing attention as a potential predictive biomarker in immune checkpoint inhibition (ICI) for head and neck squamous cell carcinoma (HNSCC). Several well-established blood-based inflammatory markers are commonly used to estimate systemic inflammatory burden. However, their utility in predicting treatment outcomes in ICI for HNSCC remains unclear. This study aimed to evaluate the predictive value of the following inflammatory indices in patients with HNSCC receiving anti-PD-1 monotherapy: C-reactive protein (CRP), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and the systemic immune inflammation index (SII). A total of 79 patients were included in this retrospective analysis. Optimal cutoff values were determined using receiver operating characteristic curve analysis to stratify patients into high- and low-inflammation groups. Chi-square tests were used to evaluate differences in treatment response. Progression-free survival (PFS) and overall survival (OS) were assessed and compared using Kaplan-Meier analysis and log-rank testing, alongside both univariable and multivariable Cox regression models. Elevated CRP levels were associated with a reduced disease control rate. In univariable analysis, patients in the high-inflammation groups showed significantly worse OS and PFS for all assessed inflammatory indices. In multivariable analysis, CRP and combined positive score remained independently significant predictors of both OS and PFS, while PLR was an independent predictor of OS. These findings suggest that a high level of systemic inflammation is associated with poorer outcomes during anti-PD-1 therapy in HNSCC. Among the evaluated indices, CRP stood out as an independent and clinically useful biomarker, providing a simple, widely available tool that could potentially serve as a practical instrument for clinicians in the management of HNSCC during anti-PD-1 treatment.