Prognostic significance of low pectoralis muscle mass on preoperative chest computed tomography in localized non-small cell lung cancer after curative-intent surgery

Objectives: The impact of sarcopenia on the outcome in patients following resection of non-small cell lung cancer is yet to be fully determined. This study aimed to evaluate the clinical utility of a computed tomography-based pectoralis muscle assessment, which reflects sarcopenia, to predict the risk of postoperative outcomes. Materials and methods: This retrospective study included 347 consecutive patients undergoing curative-intent resection of non-small cell lung cancer from 2009 to 2013. The pectoralis muscle index (pectoralis muscle area/ body mass index) was assessed at the level of the fourth thoracic vertebra on chest axial images. The primary outcomes were compared between the lowest gender-specific quintile (sarcopenia) and the other quintiles according to the index. The prognostic significance of low pectoralis muscle index was calculated by the Cox proportional hazards regression model. A propensity score matching analysis was performed to adjust the differences in clinical characteristics. Results: Sixty-nine patients were identified with sarcopenia according to the lowest gender-specific quintile of pectoralis muscle index. Patients with sarcopenia exhibited worse 5-year overall survival rate compared with patients without sarcopenia (64.2 % vs. 86.7 %, P < 0.001). Even in stage I non-small cell lung cancer, the rate of 5-year overall survival in the sarcopenia group was lower than that in the non-sarcopenia group (74.2 % vs. 92.4%, P = 0.001). Multivariate analysis revealed that low pectoralis muscle index was independently associated with adverse overall survival (hazard ratio: 2.09, 95 % confidence interval: 1.20-3.62, P = 0.009). After propensity score matching, the prognostic impact of sarcopenia based on low pectoralis muscle index was also robust for overall survival (hazard ratio: 3.23, 95 % confidence interval: 1.38-7.60, P = 0.007). Conclusions: Low pectoralis muscle index was significantly associated with poor long-term outcomes in patients with localized non-small cell lung cancer after curative surgery. This may help assist preoperative risk stratification and longitudinal management after surgery.