Presymptomatic breast cancer in Egypt: role of BRCA1 and BRCA2 tumor suppressor genes mutations detection

BACKGROUND

Breast cancer is one of the most common diseases affecting women. Inherited susceptibility genes, BRCA1 and BRCA2, are considered in breast, ovarian and other common cancers etiology. BRCA1 and BRCA2 genes have been identified that confer a high degree of breast cancer risk.

OBJECTIVE

Our study was performed to identify germline mutations in some exons of BRCA1 and BRCA2 genes for the early detection of presymptomatic breast cancer in females.

METHODS

This study was applied on Egyptian healthy females who first degree relatives to those, with or without a family history, infected with breast cancer. Sixty breast cancer patients, derived from 60 families, were selected for molecular genetic testing of BRCA1 and BRCA2 genes. The study also included 120 healthy first degree female relatives of the patients, either sisters and/or daughters, for early detection of presymptomatic breast cancer mutation carriers. Genomic DNA was extracted from peripheral blood lymphocytes of all the studied subjects. Universal primers were used to amplify four regions of the BRCA1 gene (exons 2,8,13 and 22) and one region (exon 9) of BRCA2 gene using specific PCR. The polymerase chain reaction was carried out. Single strand conformation polymorphism assay and heteroduplex analysis were used to screen for mutations in the studied exons. In addition, DNA sequencing of the normal and mutated exons were performed.

RESULTS

Mutations in both BRCA1 and BRCA2 genes were detected in 86.7% of the families. Current study indicates that 60% of these families were attributable to BRCA1 mutations, while 26.7% of them were attributable to BRCA2 mutations. Results showed that four mutations were detected in the BRCA1 gene, while one mutation was detected in the BRCA2 gene. Asymptomatic relatives, 80 (67%) out of total 120, were mutation carriers.

CONCLUSIONS

BRCA1 and BRCA2 genes mutations are responsible for a significant proportion of breast cancer. BRCA mutations were found in individuals with and without family history.

[Hereditary breast and ovarian cancer: primary and secondary prevention for BRCA1 and BRCA2 mutation carriers]

Ten years after the identification of the breast and ovarian cancer predisposition genes, BRCA1 and BRCA2, an emerging literature has explored the efficacy of strategies for primary as well as secondary prevention of breast and ovarian cancer in BRCA1 and BRCA2 mutations carriers. The integration of magnetic resonance imaging for breast cancer screening in BRCA carriers has achieved a higher sensibility of the screening, and an early detection of breast cancer. However, we don't have yet enough level of evidence that magnetic resonance imaging could reduce mortality in BRCA carriers. Because of the limitations of screening for ovarian cancer, bilateral prophylactic salpingo-oophorectomy has been established as one of the most effective strategies to prevent ovarian cancer in BRCA1 and BRCA2 mutation carriers. This strategy also has a favorable effect on the reduction of risk of breast cancer if is performed before the age of 50. The management of this patients must be individualized and multidisciplinary.