RESUMO
Objective BRCA1 is one of the most important susceptibility genes of breast cancer. The article aimed to investigate the expression of BRCA1 and its correlation in sporadic invasive breast cancer. Methods The expressions of BRCA1, ER, PR, HER2 and Ki67 in 618 cases of sporadic invasive breast cancer in our hospital from January 2015 to December 2017 were detected with immunohistochemistry in order to investigate and analyze the expression of BRCA1 and its correlation with molecular classification, histological type and other related molecular markers in sporadic invasive breast cancer. Results The positive rate of BRCA1 was 44.2% consisting of 30.3% weak positive(+) and 13.9% strong positive(++). The positive rates of ER, PR, and HER2 are 60.8%, 54.7%,and 24.9%. The proliferation index ≤30% of Ki67 was 70.7%, >30% was 29.3%. The expression of BRCA1 in luminal type A was significantly lower than the other four types of sporadic invasive breast cancer(P<0.05). The expression of BRCA1 in breast cancer with medullary histological features was significantly lower than those of the other types of breast cancer(P<0.05). There was significant difference between the expression of BRCA1 and the expressions of ER, HER2 and Ki67 (P<0.01). The expression of BRCA1 had positive correlation with expression of HER2 in sporadic invasive breast cancer (r=0.117,P<0.01). Conclusion The expression of BRCA1 in sporadic invasive breast cancer with triple negative subtype and medullary histological features is down-regulated and BRCA1 may affect the development and progression of sporadic invasive breast cancer.