The negative association between skeletal muscle and fat mass wasting caused by oesophagectomy in patients with oesophageal squamous cell carcinoma

Abstract

OBJECTIVES: This prospective observational study aimed to investigate postoperative skeletal muscle and fat mass wasting and their clinical significance in oesophageal cancer patients undergoing minimally invasive McKeown oesophagectomy. METHODS: Bioelectrical impedance analyses of body compositions were conducted before surgery and 1, 4 and 12 weeks after surgery. Curve-fitting analysis was used to describe the relationship between changes in the skeletal muscle mass index (ΔSMI) and fat mass index (ΔFMI). A logistic regression-based nomogram was established using the R tool. RESULTS: Among the 78 patients, 74.4% were male, and the mean age was 64.8 [standard deviation (SD): 6.6] years. Decreased SMIs and FMIs were concentrated in the first 4 weeks after surgery, with proportions of-3.42% (SD: 4.58) and-17.7% (SD: 11.9), respectively. A negative relationship between ΔFMI and ΔSMI was detected by linear regression (coefficient-0.341, P < 0.001). Based on the median ΔSMI to ΔFMI ratio (35.5%), 2 postoperative weight loss types were defined: SMI-dominated (SMDT) and FMI-dominated (FMDT) types. SMDT patients reported increased feeding-related problems, poorer functional status and more unhealthy symptoms than FMDT patients within 12 weeks after surgery. SMDT patients also showed poorer 2-year overall survival (71.1% vs 87.3%, P = 0.021) and disease-free survival (60.5% vs 84.9%, P = 0.032) than FMDT patients. A nomogram based on baseline and perioperative parameters was established to quantify postoperative SMDT and FMDT tendencies with good accuracy (C-index: 0.897). CONCLUSIONS: The negative relationship between ΔFMI and ΔSMI indicated differentiated metabolism post-oesophagectomy. SMDT was associated with adverse therapeutic outcomes and warranted aggressive interventions. Clinical registration number: The study protocol was registered at the Chinese Clinical Trial Registry with the registration number ChiCTR1800018511.