ERBB2 and breast cancer: Similarly, the authors observed no differences in histologic characteristics or disease-free or overall survival, but the study was limited by its small sample size (N = 134).11 In a somewhat larger retrospective cohort study, Atallah et al.12 found that pCR rates were significantly better among IHC3+ versus IHC2+/ISH+ breast cancer patients, suggesting that HER2 protein overexpression may predict response to anti-HER2 therapy.