Association between low temporalis muscle thickness and chemoradiotherapy-induced leukopenia in head and neck squamous cell carcinoma

Background: Temporal muscle thickness (TMT) is a surrogate marker of skeletal muscle mass and has been associated with survival in patients with head and neck squamous cell carcinoma (HNSCC). However, its association with adverse events during concurrent chemoradiotherapy (CCRT) remains unclear. Aims/Objectives: To evaluate the relationship between TMT and treatment-related toxicity in patients with HNSCC undergoing CCRT. Material and Methods: This retrospective study included 96 patients with HNSCC who underwent curative cisplatin-based CCRT between 2018 and 2025. TMT was measured by three independent evaluators on pre-treatment computed tomography images. A TMT cutoff value of 6.3 mm was set for men and 5.2 mm for women; accordingly, patients were stratified into low- and high-TMT groups. Results: Of the 96 patients, 54 and 42 were classified into the low- and high-TMT groups, respectively. Interobserver agreement was high (intraclass correlation coefficient = 0.853). The incidence of grade ≥3 leukopenia was significantly higher in the low-TMT group (p = 0.023). Multivariate logistic regression identified low TMT (p = 0.045) and BMI <18.5 kg/m2 (p = 0.044) as independent predictors of grade ≥3 leukopenia. Conclusions and Significance: TMT may serve as a simple imaging-based marker to aid risk stratification and guide treatment individualization in HNSCC.