Longitudinal computed tomography body composition changes in patients receiving curative radiotherapy for non-small cell lung cancer.

BACKGROUND AND PURPOSE: To determine whether longitudinal changes on routine thoracic computed tomography (CT) predict overall survival (OS) in non-small cell lung cancer (NSCLC) after curative radiotherapy and identify dose predictors of adverse tissue changes. MATERIALS AND METHODS: We performed a retrospective, single-centre study of 231 stage I-IV NSCLC patients who had at least two follow-up scans. In total, 2708 CT scans were analysed (median follow-up, 22 months; range, 1-97). Automated segmentation quantified left ventricular (LV) myocardium, L1 skeletal muscle (SKM) and fat volumes. For each tissue, baseline-normalised trajectories were used to compute monthly rates of change ("velocity"), and non-linear associations with OS were evaluated. Logistic regression identified dose metrics associated with adverse tissue change. RESULTS: SKM velocity stratified OS (C-index, 0.70): SKM loss < -0.4%/month vs ≥ -0.4%/month, HR 4.41 (95% CI 2.46-7.91, p < 0.005). LV-myocardial mass velocity showed a U-shaped relationship with OS (C-index, 0.75): atrophy < -0.3%/month vs stable, HR 4.12 (95% CI 1.65-10.27, p < 0.005); hypertrophy >0.3%/month vs stable, HR 7.90 (95% CI 2.82-22.15, p < 0.005). Dose predictors included oesophagus V10Gy for SKM loss (OR, 1.40; p = 0.03), Aorta V5Gy for myocardial atrophy (OR, 1.71; p = 0.02), and right-atrium V10Gy for myocardial hypertrophy (OR, 1.63; p = 0.02). CONCLUSION: Longitudinal CT biomarkers, particularly SKM loss rate and deviation in LV-myocardial mass, are associated with OS after curative NSCLC irradiation. These findings require validation in multicentre studies with more complete clinical information.