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

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.