Long-term changes in psoas muscle mass after lobectomy and segmentectomy for early-stage lung cancer

Background: Segmentectomy is considered a less invasive procedure than lobectomy for patients with non-small cell lung cancer (NSCLC); however, little is known about the physiological mechanism underlying the lower invasiveness of segmentectomy. This study is aimed to compare the differences in the long-term changes in the psoas muscle mass after segmentectomy and lobectomy in patients with NSCLC. Methods: Overall 315 recurrence-free patients who underwent segmentectomy (n = 93) or lobectomy (n = 222) for clinical stage 0-I NSCLC between January 2016 and December 2018 and underwent computed tomography during the entire period of 6 months <= postoperative year (POY) 0.5 < 12 months, 12 months <= POY 1 < 24 months, 24 months <= POY 2 < 36 months, and 36 months <= POY 3 < 48 months were included. Bilateral psoas muscle area (PMA) at the L3 level was measured using each cross-sectional computed tomography scan. Differences between the segmentectomy and lobectomy groups in the mean change of postoperative PMA from the preoperative period were analysed using Student's t-test and mixed analysis of variance. Multivariable analysis was performed to identify the risk factors for PMA loss on POY 3 using logistic regression analysis. Results: The lobectomy group had a significantly larger PMA change than the segmentectomy group during each postoperative period (P < 0.001). Mixed analysis of variance revealed that the mean PMA change was significantly smaller in the segmentectomy group than in the lobectomy group during the observation period (P < 0.001). The mean change in the PMA was significantly larger from POY1 (-2.5%) to POY2 (-3.9%) and POY3 (-4.7%) in the lobectomy group (P = 0.003 and P < 0.001). However, PMA remained unchanged during the postoperative observation period in the segmentectomy group. In the multivariable analysis, the risk factors for PMA change <=-3.3% (cut-off: mean change of PMA) at POY3 included lobectomy [odds ratio (OR), 3.32; 95% confidence interval (CI), 1.90-5.82; P < 0.001], male sex (OR, 1.92; 95% CI, 1.02-3.62; P = 0.044) and open thoracotomy (OR, 1.84; 95% CI, 1.11-3.05; P = 0.017). After propensity score matching, the mean change in PMA was smaller in the segmentectomy group (n = 75) than in the lobectomy group (n = 75) during the postoperative observation period (P < 0.001). Conclusions: Psoas muscle mass was better maintained during the postoperative period by segmentectomy than by lobectomy. Psoas muscle mass reduction progressed over a long postoperative period after lobectomy. Segmentectomy via complete video-assisted thoracic surgery is associated with a lower likelihood of sarcopenia progression.