Postoperative relative decrease in skeletal muscle mass as a predictor of quality of life in patients with gastric cancer

Low skeletal muscle mass reflects poor nutritional condition, which may impair the functional status and quality of life (QOL) of survivors of gastrectomy. The present cross-sectional study examined the association between a relative change in skeletal muscle mass and perceived postoperative health and QOL in patients with gastric cancer. The study comprised 74 patients (48 men and 26 women; median age, 68.5 years) who underwent surgery for stage I-III gastric cancer. Outcomes were measured using the Postgastrectomy Syndrome Assessment Scale-45, which was specifically developed to measure post-gastrectomy symptoms, living status, dissatisfaction with daily life and generic QOL. The skeletal muscle mass index (SMI) was estimated using computed tomography by tracing the area of the psoas major muscle to calculate the ΔSMI, defined as: (SMI before surgery-SMI at completion of the PGSAS-45 survey)/SMI before surgery x100. Associations between ΔSMI and health outcomes were assessed using univariate and multivariate analyses. The mean ΔSMI (SD) was 8.64% (10.6%). The effect size (Cohen's d) of ΔSMI <10% compared with ΔSMI ≥10% was 0.50 (95% CI: 0.02 to 0.97) for total symptom scores, -0.51 (-0.98 to -0.03) for general health, and -0.52 (-0.99 to -0.05) for the physical component summary (PCS). Multiple regression analysis showed that ΔSMI was significantly associated with PCS decline, and its standardized regression coefficient was -0.447 (-0.209 to -0.685). Determining ΔSMI may help clinicians to facilitate the objective evaluation of low skeletal mass, which reflects poor nutritional condition that can impair functional status and QOL of postoperative patients surviving gastrectomy.