The use of the second thoracic vertebral landmark for skeletal muscle assessment and computed tomography-defined sarcopenia evaluation in patients with head and neck cancer.

Background: The cross-sectional area (CSA) of skeletal muscle (SM) at the third lumbar vertebra (L3) is used to determine computed tomography (CT)-defined sarcopenia. We investigated the feasibility of SM assessment at the second thoracic vertebra (T2) in patients with head and neck cancer (HNC).

Methods: Diagnostic PET-CT scans were used to develop a prediction model for L3-CSA using T2-CSA. Effectiveness of the model and cancer-specific survival (CSS) were investigated.

Results: Scans of 111 patients (85% male) were evaluated. The predictive formula: L3-CSA (cm2 ) = 174.15 + [0.212 × T2-CSA (cm2 )] - [40.032 × sex] - [0.928 × age (years)] + [0.285 × weight (kg)] had good correlation r = 0.796, ICC = 0.882 (p < 0.001). SM index (SMI) mean difference (bias) was -3.6% (SD 10.2, 95% CI -8.7% to 1.3%). Sensitivity (82.8%), specificity (78.2%), with moderate agreement (ƙ = 0.540, p < 0.001). Worse 5-year CSS with lower quartile T2-SMI (51%, p = 0.003).

Conclusions: SM at T2 can be effectively used for CT-defined sarcopenia evaluation in HNC.