ERBB2 and gastric cancer: The incidence of HER2-positive gastric cancer varies considerably between studies, ranging from 6.0% to 29.5%.23–25 The main reason for this diversification is that there has not been a recognized standard examination method and objective criteria for assessing HER2-status; moreover, in AGC patients, HER2 expression is also affected by the site of the primary tumor and histological type.