Variations in vertebral muscle mass and muscle quality in adult patients with different types of cancer

OBJECTIVES: Assessment of malnutrition-related muscle depletion with computed tomography (CT) using skeletal muscle index (SMI) and muscle radiation attenuation (MRA) at the third lumbar vertebra is well validated. However, SMI and MRA values at other vertebral locations and interchangeability as parameters in different types of cancer are less known. We aimed to investigate whether adult patients with different types of cancer show differences in SMI and MRA at all vertebral levels.

METHODS: We retrospectively analyzed CT images from 203 patients:120 with head and neck cancer, esophageal cancer, or lung cancer (HNC/EC/LC) and 83 with melanoma (ME). Univariate and multivariate linear regression analyses determined the association between SMI (cm²/m 2) and MRA (Hounsfield units) and cancer type at each vertebral level (significance corrected for multiple tests, P ≤ 0.002). The multivariate analyses included age, sex, cancer stage, comorbidity, CT protocol, and body mass index (BMI) (MRA analyses).

RESULTS: SMI was lower in the HNC/EC/LC group versus the ME group at all vertebral levels, except C4 through C6 in the multivariate analyses. Female sex was associated with lower SMI at almost all levels. MRA was similar at most vertebral levels in both cancer groups but was lower at C1 through C4, T7, and L5 in the multivariate analyses. Use of contrast fluid and BMI were associated with higher MRA at all vertebral levels except T8 to T9 and C1 to C2, respectively.

CONCLUSIONS: SMI, but not MRA, was lower in HNC/EC/LC patients than in ME patients at most vertebral levels. This indicates that low muscle mass presents itself across the various vertebral muscle areas. MRA may less consistently mark muscle depletion in malnourished patients.