Several meta-analyses have reported the prevalence of HER2-low expression among HER2-negative tumors, with most of the data coming from North America, Asia, and Europe: Yang et al. [34] found a prevalence of 43.02% for HER2-low tumors among 78,984 HER2 negative BC; Ergun et al. [35] found that the proportion of HER2-low cases was 65% among 636,535 individuals; Tang et al. [36] analyzed 677,248 cases finding that the prevalence of HER2-low was 65.91%; 1’697,079 tumors were analyzed in the study of Molinelli et al. [37], finding a prevalence of 65.9% of HER2-low cases. This evidence concerns the gene ERBB2 and breast cancer.