The abundances of Bacteroides eggerthii (HR+HER2- vs. control, q < 0.01; HR+HER2+ vs. control, q < 0.05) and Bacteroides caccae (HR+HER2+ vs. control, q < 0.04; HR+HER2- vs. control, q < 0.05) were significantly greater in BC patients than in controls. The gene discussed is ERBB2; the disease is breast cancer.