Prognostic Impact of Low Muscle Mass and Inflammatory Markers in Stage III Nonsmall Cell Lung Cancer Turkish Oncology Group and Turkish Society of Radiation Oncology Thoracic Cancer Study Group (08-005).

Objectives: The aim of this retrospective multicenter study was to evaluate the prognostic significance of low muscle mass, and inflammatory markers in patients with stage III nonsmall cell lung cancer (NSCLC) who received definitive chemoradiotherapy (CRT). Furthermore, the study aimed to determine the threshold value of disease-specific low muscle mass.

Methods: A total of 461 patients with stage III NSCLC were evaluated. Low muscle mass, prognostic nutritional index (PNI), and biochemical inflammatory markers were assessed. The Kaplan-Meier method and Cox regression analysis were used to analyze overall survival (OS) and progression-free survival (PFS).

Results: This study found a disease-specific low muscle mass threshold of LSMI <38.7 cm²/m² for women and <45.1 cm²/m² for men, with 25.2% of patients having disease-specific low muscle mass. Multivariate cox regression analysis revealed that low PNI was found to be an independent unfavorable prognostic factor for both PFS (HR=0.67; 95% CI: 0.48-0.92, P= 0.015) and OS (HR=0.67; 95% CI: 0.50-0.91, P=0.008). Other factors including ECOG PS 3 (HR=7.76; 95% CI: 1.73-34.76, P=0.007), induction CT (HR=0.66; 95% CI: 0.49-0.88, P= 0.004), and disease-specific low muscle mass (HR=1.40; 95% CI: 1.02-1.92, P= 0.038) also had independent effects on prognosis.

Conclusions: The present study provides evidence that the presence of low muscle mass and low PNI significantly impacts the prognosis of patients with stage III NSCLC who undergo definitive CRT. Furthermore, our study is notable for being the first multicenter investigation to identify a disease-specific low muscle mass threshold.