Prognostic impact of CT-defined sarcopenia and prognostic nutritional index in immune checkpoint inhibitor-treated head and neck squamous cell carcinoma: A systematic review and meta-analysis.

Immune checkpoint inhibitors (ICIs) have become a standard treatment for recurrent or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC), yet survival outcomes remain highly heterogeneous, and reliable host-related prognostic biomarkers are lacking in the immunotherapy era. Growing evidence suggests that nutritional status and body composition may influence immune competence, treatment tolerance, and survival, although data specific to ICI-treated HNSCC are fragmented. We conducted a systematic review and meta-analysis in accordance with PRISMA 2020 guidelines to evaluate the prognostic impact of pretreatment CT-based sarcopenia defined by skeletal muscle index (SMI) and the prognostic nutritional index (PNI) on overall survival (OS) in patients with HNSCC treated with ICIs. PubMed and Embase were searched, and hazard ratios (HRs) with 95% confidence intervals (CIs) were pooled using random-effects models. Study quality was assessed using the Newcastle-Ottawa Scale. Nine studies met the inclusion criteria, of which four evaluated CT-based sarcopenia and five evaluated PNI. In analyses restricted to multivariable-adjusted estimates, pretreatment sarcopenia was significantly associated with poorer OS (HR 2.05, 95% CI 1.48-2.84), with no evidence of heterogeneity. In a prespecified secondary meta-analysis, low PNI was also associated with inferior OS (HR 3.67, 95% CI 2.52-5.32). Sensitivity analyses confirmed the robustness of the pooled estimates. Overall methodological quality was moderate to high. Together, these findings indicate that structural muscle depletion and immune-nutritional impairment represent complementary dimensions of host vulnerability in ICI-treated HNSCC. These readily available host-related markers may support prognostic stratification and hypothesis generation.