EGFR and esophageal squamous cell carcinoma: These studies [20–23] suggested that ESCC is more sensitive to EGFR TKIs than adenocarcinoma, which was also observed in the erlotinib Phase II trial in esophageal cancer, with 2 responses observed in 13 patients living with squamous carcinoma, and no responses observed in the 17 patients with adenocarcinoma.