Clinical Significance of Area of Psoas Major Muscle on Computed Tomography after Gastrectomy in Gastric Cancer Patients

Background: The measurement of a single abdominal image on computed tomography (CT) can provide an estimate of the total body skeletal muscle. We evaluate the change of the area of the psoas major muscle (PMMA) in a CT which was performed routinely after gastrectomy in gastric cancer. Methods: A total of 119 gastric cancer patients who underwent gastrectomy were enrolled for the study. A CT image at the top of the iliac crest level was obtained at the following times: 3 postoperative months (POM), 6 POM, 1 postoperative year (POY), 2 POY, 3 POY, and 5 POY. We analyzed the change rate of PMMA after gastrectomy and before or after recurrence. Results: PMMA change after gastrectomy was approximately between -8 and -10% over the 5-year observation period. PMMA in the R2 (macroscopic residual tumor)/recurrence group was lower than that in the no recurrence group, and a significant difference was observed at 2 POY (-21.7 ± 3.6% vs. -7.9 ± 2.3%, p < 0.01). PMMA after freshly diagnosed recurrence had decreased significantly by 14.1 ± 1.8% (p < 0.01). Conclusions: Evaluation of PMMA change by CT after gastrectomy could assist in the diagnosis of the progression of cancer state in gastric cancer patients.