Impact of pectoralis major muscle mass decrease after lobectomy on the prognosis of lung cancer

Low preoperative skeletal muscle mass is a negative prognostic factor for non-small cell lung cancer. However, the clinical significance of postsurgical skeletal muscle loss remains unclear. We investigated the impact of a postoperative decrease in pectoralis major muscle mass on long-term outcomes. A retrospective evaluation was conducted on 460 patients with pathological stage I-II non-small cell lung cancer who underwent lobectomy. Patients were categorized into two groups based on whether they did or did not show a decrease in pectoralis major muscle mass 12 months postoperatively, using a muscle mass change rate of 0.94 as the cutoff. The group showing a decrease in muscle mass (n = 126) exhibited a higher incidence of chronic obstructive pulmonary disease than the group showing no decrease in muscle mass (n = 334). The median rate of change in the muscle mass of the pectoralis major was 1.00. The median follow-up period was 42.8 months. Overall survival was significantly lower in the group showing a decrease in muscle mass than in the group showing no decrease in muscle mass (P < .001). Multivariable Cox regression analysis revealed that a decrease in pectoralis major muscle mass after surgery was an independent prognostic factor for overall survival (hazard ratio, 1.05; 95% confidence interval, 1.03-1.06; P < .001). A decrease in pectoralis major muscle mass following lobectomy is associated with poor prognosis in patients with non-small cell lung cancer.