Session Item

In-field relapses occur in around 30% of non-small cell lung cancer (NSCLC) patients treated with definitive radiochemotherapy (RCT). Changes in body composition (BC) may underpin biological processes that impact the radiosensitivity of NSCLC. We investigated potential associations between BC and in-field recurrence in patients managed with RCT for stage III NSCLC.

This retrospective, single-center study enrolled 34 patients treated with radical RCT with mean PTV doses of 60-66 Gy. Using CT imaging, total body subcutaneous and visceral adipose tissue (SAT, VAT), and skeletal muscle (SM) volumes were manually quantified at the 3rd lumbar vertebra level using SliceOmatic software. Body composition values were normalized considering gender and age-dependent variability against published demographically adjusted population reference curves obtained in > 12.000 non-cancer individuals (Magudia et al. Radiology 2020). Low body composition scores were defined as values below the 25th centile for all evaluated body composition parameters (SM, SAT and VAT).

After a minimum follow-up of 4 years, in-field recurrence occurred in 19/34 cases (56%). Low body composition scores for SM, SAT and VAT were observed in 24% (8/34), 68% (23/34), and 47% (16/34) of patients, respectively. In-field recurrence was observed in the entire low SM subgroup (8/8 patients). In the univariate analysis, low SM was associated with a higher risk of in-field recurrence (p=0.014). GTV volume did not significantly differ between patients with and without in-field recurrence (p = 0.650). In a logistic regression model, low SM was predictive for in-field recurrence (p = 0.012), independently of sex, age, tumour histology, GTV volume, and smoking. Low SAT or VAT did not correlate with the risk of an in-field recurrence.

In patients with stage III NSCLC treated with RCT, low skeletal muscle, but not SAT or VAT, was independently associated with an increased risk of an in-field recurrence.