Relationship between CD44⁺/CD24^- Phenotype and BRCA1，basal-like Breast Cancer

Objective：To study the expression of CD44⁺/CD24^- phenotype and its association with the basal-like breast cancer and BRCA1 in breast cancer．Methods：Using immunostaining ER,PR,HER2 and CK5/6 to classify the material into five tumor subgroups: basal-like subgroup,Luminal A subgroup,Luminal B subgroup,Her2 over- expressing subgroup and normal breast-like subgroup.Double-staining immunohistochemistry (IHC) was applied to the detection of CD44⁺/CD24^-cells and single-staining(IHC) for CK5/6,BRCA1.The correlations of the expression of the CD44⁺/CD24^- to basal-like and BRCA1-associated breast cancer were analyzed. Results ：In 217 cases of breast cancer, Luminal A subgroup: 130 cases,Luminal B subgroup: 15 cases,Her2 over-expressing subgroup: 21 cases,basal-like subgroup:29 cases,Normal breast-like subgroup:22 cases.BRCA1-associated breast cancer:57 cases.The expression rates of BRCA1 was low in basal-like breast cancer, which was significantly different from the other subgroups (P<0.001).The expression rates of CD44⁺/CD24^- phenotype was high in basal-like breast cancer (20/29,69%)and BRCA1-associated breast cancer(53/57,93%), which was significantly different from the other subgroups (P=0.003). Conclusion ：The mutation of BRCA1 is association with basal-like breast cancer;and the CD44⁺/CD24^- breast cancer stem cells in tumor tissue is association with BRCA1-associated breast cancer and basal-like breast cancer.