Longitudinal changes in skeletal muscle mass in patients with advanced squamous cell lung cancer

BACKGROUND: Skeletal muscle depletion (sarcopenia) is associated with poor prognosis in patients with lung cancer. We analyzed changes in skeletal muscle area using serial computed tomography (CT) until the death of patients with advanced squamous cell lung cancer (SQCLC). METHODS: This retrospective study comprised 70 consecutive patients who underwent palliative chemotherapy for SQCLC. The cross‐sectional area of the skeletal muscle at the level of the first lumbar vertebra (L1) was measured using chest CT. An artificial intelligence algorithm was developed and used for the serial assessment of the muscle area. Sarcopenia was defined as an L1 skeletal muscle index <46 cm(2)/m(2) in men and < 29 cm(2)/m(2) in women. RESULTS: The median age was 69 years; 62 patients (89%) had metastatic disease at the time of initial diagnosis. Sarcopenia was present in 58 patients (82.9%) at baseline; all patients experienced net muscle loss over the disease trajectory. The median overall survival was 8.7 (95% confidence interval 5.9–11.5) months. The mean percentage loss of skeletal muscle between the first and last CT was 16.5 ± 11.0%. Skeletal muscle loss accelerated over time and was the highest in the last 3 months of life (p < 0.001). Patients losing skeletal muscle rapidly (upper tertile, >3.24 cm(2)/month) had shorter overall survival than patients losing skeletal muscle slowly (median, 5.7 vs. 12.0 months, p < 0.001). CONCLUSIONS: Patients with advanced SQCLC lose a significant amount of skeletal muscle until death. The rate of muscle area reduction is faster at the end of life.