Abstract: ObjectiveTo investigate the expressions and significance of CD109， high molecular weight cytokeratin（HMW-CK），vimentin，p63 and antrogen receptor（AR） in basal-like breast cancer（BLBC）. Methods ER and PR-negative and CK5／6 and／or EGFR-postive expression was defined as BLBC. Immunohistochemical method was used to determine the expressions of CD109，HMW-CK，vimentin，p63 and AR in 86 cases of BLBC，compared with 57 cases of luminal type and 33 cases of HER-2 over-expressed breast cancer. Results The positive rates of CD109 were 61.6％，8.8％ and 9.1％ in BLBC，luminal type and HER-2 over-expressed breast cancer，while HMW-CK were 90.7％，26.3％ and 33.3％，and AR were 31.4％，71.9％ and 42.4％. There was significant difference among them（P＜0.01）. The positive rates of vimentin was 57.0％，42.1％ and 51.5％，and p63 were 31.4％，29.8％ and 24.2％ respectively. The difference was not significant among them（P＞0.05）. The expression of CD109，HMW-CK，vimentin and p63 were not correlated to age，tumor size，histological grade and lymphadenopathy. AR was correlated to histological grade in BLBC.
Conclusion CD109 and HMW-CK are the specific markers for the diagnosis of BLBC，while vimentin and p63 are not. The lack of AR expression in BLBC is related to invasion of tumor and malignant phenotype.