The impact of radiation to epicardial adipose tissue on prognosis of esophageal squamous cell carcinoma receiving neoadjuvant chemoradiotherapy and esophagectomy

The epicardial adipose tissue (EAT), mainly composed of brown adipose tissue, is a metabolically active tissue releasing various bioactive factors with a critical role in metabolic diseases. The EAT is often irradiated during radiotherapy in patients with esophageal cancer due to its proximity to the target region. We aimed to evaluate the effect of radiation to the EAT on survival outcomes in patients with esophageal cancer receiving neoadjuvant chemoradiotherapy followed by esophagectomy. We analyzed data on 36 patients with esophageal cancer treated with trimodal therapy between 2012 and 2017. The median follow-up period was 22.0 months. The 3-year overall survival and progression-free survival rates were 39.7% and 32.5%, respectively. Multivariate analysis revealed that higher EAT-REI was independently associated with worse overall survival (hazard ratio: 1.002, p = 0.028) and progression-free survival (hazard ratio: 1.002, p = 0.03). The cutoff value with the highest accuracy for avoiding mortality was EAT-REI = 68.8 cGy/mL (area under the curve, 0.78, p = 0.006). The 3-year overall survival rate in patients with EAT-REI ≥68.8 and <68.8 was 21.7% and 71.9%, respectively (p = 0.003). The EAT should be considered an organ at risk during radiotherapy in patients with esophageal cancer. EAT-REI might serve as a biomarker of survival outcomes in these patients.