The proportion of luminal A IBCs was reported to be as low as 7.7% in one study [24], which is significantly lower than the approximately 30% [8] expected to demonstrate HR+HER2− histopathology, suggesting a molecularly more aggressive phenotype in HR+HER2− IBCs than would otherwise be expected in non-IBC breast cancers. This evidence concerns the gene ERBB2 and breast carcinoma.