Association between masseter muscle sarcopenia and postoperative pneumonia in patients with esophageal cancer

Abstract

Sarcopenia affects the swallowing and chewing muscles, such as the masseter muscle. However, the significance of masseter muscle loss in pneumonia remains unclear. We investigated the effects of masseter muscle sarcopenia (MMS) on postoperative pneumonia in patients with esophageal cancer. In this retrospective cohort study, we analyzed the data of 86 patients who underwent esophagectomy for stage I-III esophageal cancer at our hospital between March 2013 and October 2021. The primary endpoint was postoperative pneumonia within 3 months of surgery. MMS was defined as a (1) masseter muscle index (MMI) that was less than the sex-specific MMI cutoff values, and (2) sarcopenia diagnosed using the L3-psoas muscle index (L3-PMI). Postoperative pneumonia was noted in 27 (31.3%) patients. In multivariate analysis, FEV_1.0 < 1.5 L (odds ratio, OR: 10.3; 95% confidence interval, CI 1.56-67.4; p = 0.015), RLNP (OR: 5.14; 95%CI 1.47-17.9; p = 0.010), and MMS (OR: 4.83; 95%CI 1.48-15.8; p = 0.009) were independent risk factors for postoperative pneumonia. The overall survival was significantly worse in patients with pneumonia (log-rank: p = 0.01) than in those without pneumonia. Preoperative MMS may serve as a predictor of postoperative pneumonia in patients with esophageal cancer.

Figure 1

Kaplan–Meier survival curves with log-rank test. (a) Comparison of disease-free survival after esophagectomy between patients with pneumonia and those without pneumonia. (b) Comparison of overall survival after esophagectomy between patients with pneumonia and those without pneumonia. (c) Comparison of overall survival after esophagectomy between patients with pneumonia in the acute phase and those without pneumonia in the acute phase. (d) Comparison of overall survival after esophagectomy between patients with pneumonia in the subacute phase and those without pneumonia.

Figure 2

(a) The masseter muscle area was calculated 2 cm below the zygomatic arch on the right using the following formula: length of the major axes (continuous line) × the length of the minor axes (dotted line).  (b) The psoas muscle area was calculated at L3 on the right using the following formula: length of the major axes (continuous line) × the length of the minor axes (dotted line).