Abstract: Background and purpose: BRCA1 and BRCA2 are two most common genes associated with hereditary breast cancers. Our research intended to discover the pathologic features of Chinese breast cancers with BRCA1/2 mutations. Methods: We included 287 breast cancers between 2011 and 2017, and BRCA1/2 germline mutation tests were carried out. The pathologic features of each patient were collected at Department of Pathology in Fudan University Shanghai Cancer Center for comparative study. Results: Of the 287 breast cancers, 66 cases were BRCA1 mutation positive, 47 cases were BRCA2 mutation positive and 174 cases were BRCA1/2 mutation negative. BRCA1 mutation breast cancer had higher nuclear grade tumors than the other two groups (P<0.001), 72.7% of BRCA1 mutation breast cancers were, whereas 25.5% of BRCA2 and 19.0% of non-BRCA1/2 mutation breast cancers were triple negative (P<0.001). BRCA1 and BRCA2 mutated breast cancers had lower human epidermal growth factor receptor 2(HER2) expression than non-BRCA1/2 mutated breast cancers (P<0.001). The positive expressions of cytokeratin 5/6 (CK5/6) and epidermal growth factor receptor (EGFR) in BRCA1 mutation breast cancer were about 50%, significantly higher than those of the other two groups (P<0.001), and androgen receptor (AR) positive was less frequently seen in BRCA1 mutation breast cancers. Conclusion: These results suggest that BRCA1 mutation-associated breast cancers had clinical pathologic characteristics, such as triple negative, more positive CK5/6 or EGFR status. BRCA1/2 mutated breast cancers had lower HER2 expression.

Key words: BRCA1 gene, BRCA2 gene, Breast cancer, Pathology