[Relationship between breast cancer molecular subtypes with clinicopathological characteristics and prognosis]

This study try to subclassify breast cancer into different prognostic subgroups according to immunohistochemical algorithm and discuss the relationship between subtypes and biological and clinical behavior and prognosis.

One hundred and twenty-eight cases of infiltrative ductal carcinoma were studied using immunohistochemical staining with an antibody panel of ER, PR, HER2 and CK5/6 and subclassified referring to previous reports, and the 9 cases of HER2 positive subtype were tested using FISH.

The expression of ER, PR, HER2, and CK5/6 was detected in 67%, 45%, 27% and 27% cases, respectively. All cases were subclassified into five subgroups, with luminal A (55%), luminal B (20%), HER2 positive (7%), basal-like (10%) and unclassified cases (8%). Nine HER2 positive cases all showed amplification of HER2 gene. It was demonstrated that the luminal A group was associated with the best prognosis but the basal-like group worst by univariate analysis. Multivariate analysis demonstrated that both the clinical stage and immunohistochemical subtypes of tumor were related to overall survival. Menses status were different among these subtypes.

According to the expression of ER, PR, HER2 and CK5/6, infiltrative ductal carcinoma could be subclassified into five subgroups with different biological features and outcome, having a role in evaluating the prognosis and guiding the clinical treatment.