ERBB2 and breast cancer: In the present study, LVI was present in 33.2% (530/1594) of HER2-positive BC—35.2% (189/537) of ER-positive and 32.3% (341/1056) of ER-negative tumors In the subgroup of pT1a-b BC, LVI was present in 10.5% (36/344) of pN0 BC and 31.1% (14/45) of pN0(i+) and pN1mi BC.