It is intriguing that women with HER2+ compared to those with HER2− breast cancer displayed lower abundance of select genera of Firmicutes (e.g., g_Clostridium, g_Blautia, g_Coprococcus, g_Ruminococcus, g_SMB53) and higher abundance of select genera of p_Bacteroidetes; thus a deficit of taxa that have often been linked with healthy body composition, body leanness and healthy metabolic profile [37, 38]. This evidence concerns the gene ERBB2 and breast cancer.