[Biological characteristics of triple negative breast cancer with low expression of HER2].

There are some differences of histological morphology and genetic variation between HER2-negative group and HER2-low group, and also differences in genetic variation between HER2 1+ and HER2 2+ in HER2-low group, which are helpful for more accurate stratification of TNBC and useful for finding the therapeutic target and precise treatment of HER2-low TNBC.