This could partially be explained by the more enrollment of HR-negative patients in HER2-0 group and enrollment of stage IV patients in both groups, as genetic alteration patterns are significantly different in HR + breast cancer compared with HR− breast cancer50 and genetic alteration patterns are significantly different in EBC compared with advanced breast cancer.51 This implies that HER2-low EBC may exhibit a distinct genetic alteration from HER2-0 EBC, but this needs to be confirmed by large-scale genome sequencing. The gene discussed is ERBB2; the disease is breast cancer.