Breast cancer involves abnormal cells growing uncontrollably in the breast, forming tumors. These cells can originate in milk ducts or lobules and may spread. HER2-positive breast cancer is a type characterized by elevated levels of a specific protein. Understanding this protein’s nature is important for guiding treatment.
Understanding HER2 Breast Cancer
HER2 stands for Human Epidermal growth factor Receptor 2. It is both a gene and a protein found on the surface of breast cells. Normally, HER2 proteins act as receptors, receiving signals that help regulate cell growth and division.
In some breast cancers, the HER2 gene has extra copies, leading to an overproduction of the HER2 protein. This overexpression results in excessive signaling, promoting uncontrolled cell growth and tumor progression.
About 15% to 20% of invasive breast cancers are classified as HER2-positive. These cancers tend to grow and spread more rapidly than other types of breast cancer.
Is HER2 Overexpression Inherited?
HER2 overexpression in breast cancer is primarily an acquired genetic change, meaning it is not typically inherited from parents. This alteration usually occurs as a somatic mutation or gene amplification within cancer cells during a person’s lifetime. Somatic mutations are genetic changes that happen in individual cells after conception and are not passed down to offspring. While very rare instances of germline (inherited) HER2 mutations have been identified in other cancers, they are not the typical cause of HER2-positive breast cancer. The vast majority of HER2-positive breast cancers arise from genetic changes that develop spontaneously within the tumor cells.
Genetic Predisposition for Breast Cancer
While HER2 overexpression is generally not inherited, breast cancer can have a hereditary component. This involves inherited mutations in other specific genes that significantly increase a person’s risk of developing breast cancer. These inherited genetic changes are called germline mutations because they are present in all cells of the body, passed down from a parent.
Examples include BRCA1 and BRCA2, which normally help repair damaged DNA and suppress tumor growth. When mutations occur in these genes, the risk of developing breast cancer and other cancers, like ovarian cancer, increases substantially.
Other genes associated with an increased hereditary breast cancer risk include TP53, PALB2, CHEK2, ATM, CDH1, and PTEN. These genes are distinct from the HER2 gene and predispose individuals to breast cancer in general, not specifically HER2-positive breast cancer.
Considering Genetic Testing and Counseling
Genetic testing and counseling are important for individuals concerned about an inherited risk of breast cancer, particularly concerning genes like BRCA1 and BRCA2. Testing is typically recommended for those with a strong family history of breast or ovarian cancer, early-onset breast cancer, or multiple primary cancers.
Genetic counseling provides a comprehensive risk assessment, helps individuals understand test results, and guides them through complex genetic information. Genetic testing identifies inherited gene mutations, allowing for personalized risk management and screening strategies.
These may include earlier or more frequent mammograms or magnetic resonance imaging (MRI) screenings, and in some cases, preventive surgeries. This genetic testing focuses on inherited predispositions to breast cancer and is separate from tumor testing to determine HER2 status.