After another block was detected for the cases with double-equivocal HER2 status in 333 breast cancers in initial blocks of our cohort, 19 HER2 amplification was distinguished (5.7%, 19/333), including 8 FISH group 1 and 11 FISH group 3, and only 4 cases of obvious different results of HER2 status between two blocks was found (1.2%, 4/333) (cases 5, 6, 18, 19 in Table 1). Here, ERBB2 is linked to breast cancer.