Risk factors for esophageal fistula in thoracic esophageal squamous cell carcinoma invading adjacent organs treated with definitive chemoradiotherapy: a monocentric case-control study

Background Standard treatment for unresectable esophageal squamous cell carcinoma (ESCC) without distant metastasis is definitive chemoradiotherapy (dCRT), in which the incidence of esophageal fistula (EF) is reported to be 10–12%. An ad hoc analysis of JCOG0303, a phase II/III trial of dCRT for patients with unresectable ESCC (including non-T4b), suggested that esophageal stenosis is a risk factor for EF. However, risk factors for EF in patients limited to T4b ESCC treated with dCRT have yet to be clarified. The aim of this study was to investigate risk factors for EF in T4b thoracic ESCC treated with dCRT.