BRCA1 tumor expression and clinical results in Uruguayan patients diagnosed with breast cancer before the age of 40

BRCA1 mutations are rare in sporadic breast cancer (CM), however their expression at the tumor level is diminished or absent in 30-50% of cases. Objective: to assess the tumor expression of BRCA1 using immunohistochemistry (IHC) in Uruguayan women diagnosed with BC before the age of 40 years. Material and methods: patients diagnosed with BC before the age of 40 between. The antibodies used were anti BRCA1 MS110 monoclonal antibodies against the N-terminal end and GLK-2 against the C-terminal. Overall survival (OS) and disease free survival (DFS) were calculated; the curves were developed using the Kaplan-Meier method and the difference in survival was evaluated through the log rank test. Results: the average age of the 40 patients included was 36 years. The 5-year OS and DFS were 73% and 60% respectively. The expression of BRCA1 with GLK-2 was <= 10% in 16 of the 40 patients included (40%). The 5-year OS and DFS for patients with <= 10% expression was 56% vs. 85% for patients with >10% (p=0.015) and 40% vs. 72% (p = 0.034) respectively. The expression of BRCA1 by MS110 was <= 10% in 11 of the 40 patients included (27.5%). No differences were found in the 5-year OS or DFS based on the expression of this marker. Conclusion: The loss of BRCA1 expression using GLK-2, which suggests the presence of a truncated protein, was associated with a statistically significantly lower OS and DFS, that the decrease in the BRCA1 protein as determined by GLK2 has an unfavorable prognostic value for young patients with BC.