Inflammatory markers as prognostic markers in patients with head and neck squamous cell carcinoma treated with immune checkpoint inhibitors: a systematic review and meta-analysis

Background Various inflammatory markers, including neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR), and C-reactive protein-to-albumin ratio (CAR), have been linked to the effectiveness of immunotherapy in multiple types of malignancies. We investigated how these inflammatory markers affect the prognosis of patients with head and neck squamous cell carcinoma (HNSCC) receiving immunotherapy. Methods The databases PubMed, Embase, and Cochrane were systematically searched up until March 26, 2024, to identify relevant literature. Hazard ratios (HR) and corresponding 95% confidence intervals (CI) were extracted from the eligible studies. Data analysis was conducted using Review Manager and STATA 17.0 software to assess the impact of each indicator on prognosis. Subgroup analysis was performed to explore potential sources of heterogeneity in the data. Results The analysis included sixteen studies with 1316 patients. A higher baseline NLR was significantly associated with poorer overall survival (OS) (pooled HR: 1.55, 95%CI: 1.14-2.11, P=0.006) and progression-free survival (PFS) (pooled HR: 1.59, 95% CI: 1.21-2.10, P<0.05). Furthermore, a high NLR after immunotherapy was strongly correlated with poor OS (pooled HR: 5.43, 95% CI: 3.63-8.12, P<0.01). Additionally, higher baseline C-reactive CAR was significantly associated with worse OS (pooled HR: 2.58, 95% CI: 1.96-3.40, P<0.01). Conclusion The inflammatory markers NLR and CAR serve as effective prognostic biomarkers for immunotherapy in patients with HNSCC. However, the practical application of clinical detection requires further validation through large-scale prospective studies to confirm these findings and explore the underlying mechanisms.