Результаты иммуногистохимической диагностики рака молочной железы в Гродненской области с учетом мутации BRCA1 в тройном негативном раке

Background: The results of immunohistochemical (IHC) assessment in breast cancer may determine not only the outcome, but also the main directions of antitumor treatment. Aim : To study the results of IHC diagnosis of breast cancer in the Grodno region in 2010 to 2015, to determine the frequency of the BRCA1 gene mutations in triple-negative breast cancer. Materials and methods : 2008 cases of estrogen receptor and/or progesterone receptor positive and 2445 cases of HER2/neu expressing breast cancer were extracted from the database and IHC laboratory journals of the Grodno Regional Clinical Bureau for Pathological Anatomy. Standard DAKO kits (Denmark) were used for IHC. Molecular genetic studies of DNA samples for the presence of the BRCA genes mutations were done by polymerase chain reaction in 449 women with breast cancer. BRCA1 mutation was assessed in 39 cases of triple-negative breast cancer. Results: HER2/neu overexpression (3+) was found in 25.5% (622/2445) of all breast cancer cases, whereas of estrogen receptor and progesterone receptor positive tumors in 50.05% (1105/2008) of cases. Triple negative breast cancer was diagnosed in 19.8% (398/2008) of cases, and the mean age of the patients at the diagnosis was 56.2 years. The BRCA1 gene mutations were identified in 5 of 39 (12.8%) cases of triple negative breast cancer, which is significantly more often than in women with breast cancer without consideration of their hereditary predisposition (17/449, or 3.8%; χ2 = 4.87, p = 0.0274). Histological examination showed that among the tumors with the BRCA1 mutations, there were 3 cases with invasive ductal cancer (one G2 and two G3), one with medullary and one with undifferentiated G3 cancer. One patient had a metachronous bilateral lesion. Conclusion: In the region of Grodno, 50% of breast cancer patients would need hormonal therapy, 25% would need treatment with trastuzumab, and 20% with cytostatic agents. The prevalence of the BRCA1 mutation in triple negative breast cancer is higher compared to that in breast cancer patients without consideration of their hereditary predisposition.