Moreover, we compared serum HER2 level ininvasive and non-invasive ductal carcinoma and found that serum HER2 levels werehigher in patients with invasive ductal carcinoma than patients with ductalcarcinoma in situ, but no significant difference was revealed between these twogroups since there were only 8 cases of ductal carcinoma in situ (Table 2). Here, ERBB2 is linked to invasive ductal breast carcinoma.