Impact of Preoperative Skeletal Muscle Mass on Prognosis and Postoperative Change in Patients With Gastrointestinal Cancer

BACKGROUND: Skeletal muscle mass is a critical prognostic factor across various cancers; however, its differential impact on survival outcomes and the nature of postoperative changes remains inadequately explored. This study investigates the influence of preoperative skeletal muscle mass on survival and postoperative trends in skeletal muscle mass across gastrointestinal cancer types. METHODS: The total psoas major muscle volume (TPV) was utilized as a skeletal muscle index, obtained from CT images of patients with gastrointestinal cancer. TPV measurements were extracted at multiple time points to assess changes over time. RESULTS: A total of 1798 patients were included (esophageal: 554; gastric: 539; colorectal: 705). Patients with low skeletal muscle mass exhibited poorer prognoses across all cancer types. Among these, 969 patients (esophageal: 307; gastric: 278; colorectal: 384) had available postoperative follow-up CT scans at 1, 2, and 3 years. Annual decreases in TPV were observed across all cancer types; however, patients with colorectal cancer demonstrated a smaller decline in skeletal muscle mass compared to those with esophageal and gastric cancers (p < 0.05). In gastric and esophageal cancer patients, TPV was significantly lower in those with recurrence. Additionally, in gastric cancer, the reduction in TPV after distal gastrectomy was less than that observed after proximal or total gastrectomy. CONCLUSION: This study underscores the prognostic significance of skeletal muscle mass in gastrointestinal cancer and its dynamic postoperative changes, highlighting the need for further investigation to enhance patient outcomes as the global cancer burden increases.