16S ribosomal RNA (rRNA) gene amplicon sequencing was conducted on normal tissue (n = 8), normal adjacent tissue (normal pairs, n = 11), and breast tumors (n = 64), with a total of 13 stage 1, 24 stage II, and 19 stage III and IV breast cancer tissues analyzed by 4 subtypes of luminal A, luminal B, human epidermal growth factor receptor 2 (HER2), and triple negative breast cancer (TNBC), from non-Hispanic Black and non-Hispanic White women (17). This evidence concerns the gene ERBB2 and breast cancer.