ERBB2 and breast cancer: Finally, at the species level, significant increases in the abundances of Bifidobacterium adolescentis (control vs. HR+HER2-, q < 0.05; control vs. HR+HER2+, q < 0.05) and Bifidobacterium longum (control vs. HR+HER2-, q < 0.01; control vs. HR+HER2+, q < 0.05) were detected in the control group compared to the BC group.