Associations between the expression of mucins (MUC1, MUC2, MUC5AC and MUC6) and clinicopathologic parameters of human breast carcinomas

Aims: The aim of this study is to evaluate the relationships between the expression of mucins in invasive breast carcinomas and clinicopathologic parameters. Materials and Methods: We examined 150 cases of invasive breast carcinoma, using the 2012 World Health Organization (WHO) classification of the tumors of the breast. We studied the expression of MUC1, MUC2, MUC5AC, and MUC6 by immunohistochemistry. We also evaluated normal breast tissue and ductal carcinoma in situ (DCIS) lesions in nearby invasive tumor areas. Results: In invasive breast carcinomas, MUC1, MUC2, MUC5AC, and MUC6 were expressed in 98.6%, 11.3%, 9.9, and 8.5% of cases, respectively. MUC2, MUC5AC, and MUC6 were overexpressed in invasive tumors and DCIS lesions were compared with normal breast tissue. The apical pattern of MUC1 was correlated with low grade and ER expression. MUC2 was correlated with mucinous carcinoma and an inverse association with invasive ductal carcinoma, not otherwise specified (NOS). MUC6 expression was associated with lymphovascular invasion. Conclusions: Most invasive breast tumors express MUC1 and the apical pattern of MUC1 is correlated with low grade and ER expression. MUC6 expression is associated with indicators of poor prognosis. Further comprehensive studies need to evaluate the role of mucins as a potential biomarker and to be used as a specific therapeutic target against breast cancer.