ERBB2 and breast carcinoma: However, median level of Firmicutes was lower among women with HER2+ than those with HER2− breast cancer (33.53 vs 51.75, p = 0.005), and also lower among women with early (≤ 11) than those with later (≥ 12) age of menarche (35.61 vs 50.17, p = 0.048) (Fig. 3).