Purpose: We aimed to assess whether skeletal muscle loss during EGFR thyrosine kinase inhibitor therapy of advance non-small cell lung cancer patients is an independent prognostic factor for progression-free survival (PFS) and overal survival (OS).
Methods: A total of 45 patients who had computed tomography images were retrospectively evaluated at the diagnosis and during the treatment period before progression occurs.
Results: During treatment 19 patients (42.2%) had skeletal muscle loss. Objective response rates in muscle loss group and muscle stable group were 36.8% and 73.0%, respectively (p<0.01). Median follow-up time was 18.9 months (14.8-32.1). Median PFS was 14.7 months (95% CI 12.1-17.3) in muscle stable group and 7.6 months (95% CI 6.7-8.5) in muscle loss group (p<0.01). Median OS was 18.3 months (95% CI 16.5-20.2) in muscle loss group while it was 30.1 months (95% CI 22.1-38.2) in muscle stable group (p<0.01). In multivariate analysis for both PFS and OS, skeletal muscle loss was an independent prognostic factor. Hazard ratios (HR) for PFS and OS were 12.2 (95% CI 4.3-34.4) and 3.51 (95% CI 1.41-8.73) respectively.
Conclusion: On CT imaging skeletal muscle loss before progression is an independent prognostic factor for both PFS and OS in advance non-small cell lung cancer patients who received EGFR tyrosine kinase inhibitor therapy.