Our results show that the possibility of using AR and microRNAs as markers depends on the tumor subtype: a decrease in AR expression may be the marker for the presence of lymph node metastases in patients with HER2-positive subtypes of breast cancer, and disturbance of miR-205, miR-185, and miR-21 expressions may be the marker in patients with a luminal B HER2-positive subtype. The gene discussed is ERBB2; the disease is neoplasm.