Human epidermal growth factor receptor 2 expression was significantly associated with macroscopic type (23.8% in the polypoid type, 5.8% in the non-polypoid type; P=0.0078), histological classification (25% in papillary adenocarcinoma, 9.7% in well differentiated adenocarcinoma, 3.2% in moderately differentiated adenocarcinoma, 5.9% in poorly differentiated adenocarcinoma; P=0.0237), and invasion to other organs (3.9% in invasive cases, 15.1% in non-invasive cases; P=0.0242). The gene discussed is ERBB2; the disease is papillary adenocarcinoma.