Immunophenotype: There were 23 cases of HER2-zero (including 13 cases of HER2 ultra-low), 72 cases of HER2 low, 11 cases of HER2 positive, and the HER2 positive rate was 10.38%, and the incidence of low expression was 67.93%; The incidence of HER2 low in male breast cancer was significantly higher than that in female breast cancer, and the difference was statistically significant (P < 0.05). The gene discussed is ERBB2; the disease is breast carcinoma.