Likewise, the HER2/CEP17 ratios did not significantly differ if dividing group by the ratio <2 or ≥2, if extracting the ductal carcinoma in situ (DCIS) group, if dividing groups according to HER2‐IHC status 0/1+, 2+, or 3+, respectively. Here, ERBB2 is linked to ductal breast carcinoma in situ.