Body components at T12/L3 on CT and correlation with survival in esophageal cancer

This study examined whether CT metrics at the 12th thoracic vertebra (T12) can replace those at the 3rd lumbar vertebra (L3) for diagnosing sarcopenia, and analyzed their impact on outcomes in esophageal squamous cell carcinoma (ESCC).

We retrospectively reviewed 405 CT scans (person-times) of 206 ESCC patients (stages II-IV) who had received chemoradiotherapy (CRT). Metrics including Skeletal Muscle Index (SMI), Skeletal Muscle Attenuation (SMA), Intramuscular Adipose Content (IMAC), and Visceral-to-Subcutaneous Adipose Tissue Ratio (VSR) were measured at both T12 and L3. These were compared with clinical outcomes.

Significant correlations were found between body composition parameters measured at T12 and L3, with Spearman's coefficients of 0.62 for SMI, 0.72 for SMA, 0.59 for IMAC, and 0.46 for VSR (all p < 0.01). After adjusting for age, gender, and tumor stage, a low post-CRT T12 SMI was significantly associated with reduced overall survival (adjusted hazard ratio = 1.56, p = 0.04), which corresponded to low post-CRT L3 SMI (adjusted hazard ratio = 1.65, p = 0.04).

We concluded that measuring skeletal muscle at T12 can effectively diagnose sarcopenia using chest-only CT scans. Post-CRT T12 SMI may serve as a prognostic indicator for ESCC patients.

Question Assessing sarcopenia in esophageal cancer patients is crucial for prognosis, yet traditional metrics rely on the 3rd lumbar vertebra, which may not be optimal. Findings Our study demonstrates that the muscle index at the 12th thoracic vertebra correlates well with that of the 3rd lumbar vertebra, effectively predicting patient survival. Clinical relevance Evaluating sarcopenia at the 12th thoracic vertebra via chest CT offers a reliable prognostic tool for esophageal squamous cell carcinoma patients, potentially improving survival predictions after chemoradiotherapy.