ERBB2 and breast cancer: Our conclusion, that ISH-equivocal breast cancers are HER2-not-amplified is also supported by our previous data,17,18 which demonstrate that ASCO-CAP FISH group 4 (HER2-equivocal) breast cancers lack HER2 protein overexpression17,18 and have patient outcomes17 that are not significantly different from ASCO-CAP FISH group 5 (HER2-negative or HER2-not-amplified) breast cancer patients.