Familial Breast Cancer: Genetic Testing

Abstract

Abstract Hereditary breast cancer is uncommon, accounting for approximately 5–10% of all breast cancer diagnoses. However, it is critical to identify individuals with a hereditary breast cancer predisposition. These individuals can significantly benefit from altering their personal cancer surveillance plan from the general population recommendations. Individuals with a hereditary breast cancer risk should work with their clinicians to develop a personalised management plan, which may include a combination of increased screening, preventative surgeries and risk‐reducing medications. To best determine who may be at risk, what their particular risks are and the most appropriate testing strategy, a formal genetic risk assessment is needed. Genetic testing may confirm the presence of a cancer predisposition syndrome in a family, providing information regarding the cancer risks for the individual and their family members and directing appropriate clinical management. Owing to the complexities associated with this process, involvement of specially trained genetics professionals is crucial. Key Concepts: It is estimated that approximately 5–10% of breast cancers are hereditary. BRCA1 and BRCA2 are the most common genes associated with hereditary breast cancer risk. In addition to the BRCA1 and BRCA2 genes, there are several other genes that are associated with a well‐defined hereditary cancer predisposition syndrome that includes an increased breast cancer risk. Formal genetic risk assessment is helpful to determine the most appropriate and cost‐effective strategy for genetic testing. It is necessary to fully understand the implications of genetic testing results to form a comprehensive and adequate surveillance and management strategy for the individual and their family. The medical management for hereditary breast cancer predisposition syndromes includes high‐risk surveillance, prophylactic surgical options, lifestyle changes and chemoprevention. Recent studies suggest that breast cancer risk may be increased in young BRCA‐positive women who initiate screening mammograms before the age of 30. Recent studies have suggested that doubling the standard 5‐year course of tamoxifen use can reduce breast cancer recurrence and mortality in high‐risk women. Recent research has suggested that most ovarian cancers actually arise in the fallopian tube, leading researchers to propose prophylactic surgeries that may preserve the ovaries in the future. Newer data suggest that maintaining a healthy weight reduces cancer recurrence risks, and that this may be due at least in part to the role the BRCA1 gene plays in mimicking a negative energy balance within the cell.