Oncological impact of the preoperative combined assessment of skeletal muscle mass for patients undergoing curative gastrectomy for gastric cancer.

Purpose: We performed a combined assessment of skeletal muscle mass using the skeletal muscle mass index (SMI) and the psoas muscle index (PMI) to evaluate their association with the overall survival (OS) of gastric cancer patients after curative gastrectomy.

Methods: We analyzed, retrospectively, the computed tomography records of skeletal muscle mass of patients who underwent radical gastrectomy for pStage I-III gastric cancer between April, 2010 and April, 2016. We then compared OS as the primary outcome, stratifying patients according to their SMI or PMI, and investigated prognostic factors using multivariate analyses.

Results: The median follow-up duration was 62 months. Of the 550 patients analyzed, 262 (47.6%), 194 (35.3%), and 94 (17.1%) were classified into normal, single-low, and double-low SMI and PMI groups, respectively. Patients with double-low SMI and PMI had the poorest OS (P = 0.018). Multivariate analysis revealed that double-low indices were an independent prognostic factor for poor OS (hazard ratio, 1.808; 95% confidence interval 1.009-3.238; P = 0.046).

Conclusions: This study revealed that evaluation of skeletal muscle mass based on the combined SMI and PMI can predict the survival outcomes of patients after curative gastrectomy for gastric cancer, and that the coexistence of a low-SMI and low-PMI was associated with the poorest survival.