Comparing the abundance of these phyla between the study groups, there was a notable increase in Actinobacteria in the control group compared to that in the HR+HER2- BC patients (q < 0.01), as well as increased levels of Bacteroidetes in the control subjects compared to those in the HR+HER2+ BC group (p < 0.01). The gene discussed is ERBB2; the disease is breast cancer.