A RECENT study presented at the European Congress of Radiology 2026 (ECR 2026) identified important variations in thoracic body composition associated with age and smoking status in individuals undergoing lung cancer screening. The findings provide new reference points that could help improve prediction of lung cancer mortality using CT-based measures.
Researchers analysed baseline low-dose chest CT scans from participants in the NELSON lung cancer screening trial using an artificial intelligence-based automated system to assess body composition. A total of 4,435 male participants were included in the analysis, with a mean age of 59.4 years and an average smoking exposure of 42.2 pack-years.
The analysis quantified skeletal muscle area (SMA) and subcutaneous adipose tissue area (SAT) at the T5, T8, and T10 vertebral levels. Mean values across these levels were used to derive a single SMA and SAT metric for each participant, allowing calculation of the fat-to-muscle ratio (FMR).
Current vs Former Smokers: Body Composition Differences in Lung Cancer Screening
Current smokers, who represented 55% of the cohort, showed significantly lower levels of SAT, SMA, and FMR compared with former smokers (45%). Specifically, SAT measured 372 cm² in current smokers versus 441 cm² in former smokers (p<0.001), while SMA measured 501 cm² compared with 507 cm² (p<0.001). The fat-to-muscle ratio was also lower among current smokers (0.74 versus 0.87; p<0.001).
Age-related differences in body composition were also observed. Across 5-year age groups, skeletal muscle area declined steadily from 515 cm² in individuals aged 50–54 years to 472 cm² in those aged 70 years and older (p<0.001). In contrast, subcutaneous adipose tissue increased from 376 cm² to 443 cm² over the same age range (p<0.001), while the fat-to-muscle ratio rose from 0.70 to 0.90 (p<0.001). These associations remained significant after adjusting for smoking status and cumulative smoking exposure.
New Evidence Highlights Role of CT Metrics in Lung Cancer Screening
Overall, the findings indicate that increasing age is associated with progressive muscle loss and fat accumulation in men undergoing lung cancer screening, whereas current smoking is linked to lower levels of both muscle and fat compared with former smoking. According to the researchers, establishing reference values for CT-based body composition measures could support improved risk stratification in lung cancer screening populations.
However, the authors noted that further analyses are required to determine how these body composition markers relate to clinical outcomes within lung cancer screening settings.
Reference
Xin Y et al. Thoracic body composition across age and smoking status in a lung cancer screening cohort: insights from the NELSON Study. ECR Congress. 4-8 March, 2026.
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