The prognostic significance of BRCA1 gene expression in patients with breast cancer

Background. Nowadays, BRCA-associated breast cancer occupies a special position in the choice of treatment strategy. Although, the drug treatment of such patients was almost the same as the treatment of sporadic disease. Of particular interest is the assessment of the deficit of homologous recombination, which may include various dysfunctions of the BRCA1 gene. Moreover, it has been shown that a decrease in the functional activity of BRCA1 is reflected in the sensitivity of the tumor to DNA damaging agents, and the prognosis of the disease becomes more favorable.

Objective: assessment of the association of BRCA1 gene expression in a breast tumor with the prognosis of the disease.

Materials and methods. The study included 111 patients with breast cancer T1–4N0–3M0 (stage IIA–IIIB), with a morphologically verified diagnosis. Initial and postoperative expression of BRCA1 in tumor material was evaluated. RNA was isolated from the tumor material before treatment and after neoadjuvant chemotherapy. The level of BRCA1 expression was assessed using reverse transcriptase quantitative real-time polymerase chain reaction.

Results. As a result of the study, long-term results of treatment of patients were evaluated depending on the level of BRCA1 gene expression. The presence of BRCA1 hypoexpression (level less than 1) in tumor tissue after neoadjuvant chemotherapy was found to be a favorable prognostic factor and is associated with high rates of metastasis-free survival (p = 0.0002). In addition, a similar result is shown for patients treated with the FAC (fluorouracil, doxorubicin, cyclophosphamide) neoadjuvant chemotherapy regimen (p = 0.005). Despite the absence of statistically significant differences, in 8 patients who underwent chemotherapy with the inclusion of platinum drugs, there was a low level of BRCA1 expression in a residual tumor and 100 % non-metastatic and overall survival.

Conclusion. Based on the data obtained, it can be assumed that the aberrant state of the BRCA1 gene (low expression) in a breast tumor may also be a promising marker for the prognosis of the disease, which confirms the undoubted relevance of the study, but also requires further detailed study. 

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