Mutations in several genes can increase the risk of breast cancer, of which BRCA1 and BRCA2 are most closely related to this disease.
Cancer occurs when important genes that help repair DNA or control cell growth are mutated. These mutations cause cells to grow and divide uncontrollably, thereby forming cancerous tumors.
In most cases of breast cancer, the mutation will occur at some point in the patient’s life and is present only in certain breast cells. These mutations are called acquired, non-heritable mutations. In less common cases, genetic mutations occur in all cells of the body and increase the risk of developing breast cancer. These changes are classified as germline mutations and are likely to be passed on from parent to child. An estimated 5-10% of breast cancer patients are associated with genetic mutations.
Researchers have discovered many different genes that are associated with the risk of developing breast cancer. Among them, some mutations are more common than others.
BRCA1 and BRCA2
BRCA1 and BRCA2 are two important genes that have the ability to suppress tumors and fight cancer. In normal cells, these two genes help the body make proteins to repair damaged DNA. When mutated, BRCA1, BRCA2 no longer functions and functions as it should. This causes cells in the breasts, ovaries, and other organs to grow, divide quickly, or grow uncontrollably, leading to cancer.
The BRCA1 and BRCA2 gene mutations are inherited mutations. A woman who inherits the BRCA1 or BRCA2 gene mutation from one of her parents has a 70% increased risk of developing breast cancer before the age of 80. Carriers of these mutations are more likely to be diagnosed with breast cancer at a younger age, as well as have cancer in both breasts, than non-carriers of the mutation. Mutations in BRCA1 or BRCA2 also increase the risk of certain other types of cancer, such as ovarian, prostate, and pancreatic cancers.
Mutations in several other genes can also lead to breast cancer. However, these mutations are less common and do not increase breast cancer risk as much as the BRCA gene.
ATM: Gene ATM normally helps the body repair damaged DNA or kill cells if successful repair cannot be achieved. Inheriting the ATM gene mutation from one parent can increase a patient’s risk of breast cancer.
PALB2: The PALB2 gene makes a protein that combines with the protein made by the BRCA2 gene to repair damaged DNA and stop tumor growth. Defects in these genes can increase your chances of getting breast cancer. Some studies have shown that women carrying the PALB2 gene mutation have a 14% risk of developing the disease before the age of 50 and a 35% risk of developing the disease before the age of 70.
TP53: Gene TP53 helps to stop the growth of cells with damaged DNA. Inherited mutations in this gene cause Li-Fraumeni syndrome. Patients with this syndrome have a high risk of breast cancer, as well as some other types of cancer such as leukemia, brain tumor, sarcoma …
PTEN: The normal PTEN gene helps control the growth of cells. Genetic alterations in PTEN can cause Cowden syndrome, a disorder that puts patients at risk of developing tumors (both benign and malignant) in the breast, as well as in the digestive tract, thyroid, uterus and ovaries.
CDH1: CDH1 makes a protein that helps cells join together to form tissue. Women who carry an inherited mutation in this gene have a 39-52% lifetime risk of developing invasive lobular breast cancer.
STK11: Defect in the STK11 gene can lead to Peutz-Jeghers syndrome. People affected by this syndrome have pigment spots on the lips and in the mouth, tumors in the urinary and digestive tracts, as well as an increased risk of many types of cancer, including breast cancer.
PIK3CA: The PIK3CA gene provides instructions that help make a protein important for many cellular functions. The PIK3CA mutation is an acquired mutation that cannot be passed from parent to child. This gene mutation is found in about 30-40% of breast cancers. It is important for doctors to determine whether a patient carries a PIK3CA mutation so that an appropriate treatment regimen can be developed.
HER2: The HER2 gene makes a protein called HER2 (human epidermal growth factor receptor). This protein is found on the surface of all breast cells and is responsible for their growth. If the HER2 gene is faulty, they stimulate the body to make more HER2 protein, which in turn causes cells to grow out of control. Like PIK3CA, the HER2 gene mutation is not an inherited mutation. Research shows that about 10-20% of breast cancers are HER2 positive.
Phuong Quynh (According to American Cancer Society, Webmd, CDC)