ERBB2 and esophageal squamous cell carcinoma: In addition, 65 cases, including 13 HER2 overexpression (3+) cases and 52 HER2 equivocal (2+) cases from the 857-case cohort, and another 104 ESCC cases, including 1 HER2 overexpression (3+) case, 3 HER2 equivocal (2+) cases and 100 HER2 negative (1+/0) cases, were selected to construct tissue microarrays (TMAs).