Because HER2-enriched and IC5 tumors tended to be HR- (48.4% of HER2-enriched vs 33.3% of other, χ2 p = 0.16; 48.4% of IC5 vs 16.7% of other, p = 0.0096) and to have higher HER2 FISH ratios (mean HER2 FISH ratio 7.4 in HER2-enriched vs 5.8 in other, two-sided t-test p = 0.050; 7.5 in IC5 vs 4.2 in other, p = 1.7e-5), it is plausible that these clinically assessed variables dictate in part the association between tumor subtype and pCR. The gene discussed is ERBB2; the disease is neoplasm.