Other Breast Cancer Genes
Family history is one of the unavoidable genetic risk factors for developing breast cancer. Ongoing research is helping identify the genes that are responsible for this inherited increased risk. BRCA1 and BRCA2 gene mutations are currently the best-known and most discussed genetic risk factors, but new genetic links are being discovered regularly.
Below are a number of other genes that are known to influence breast cancer risk. In each case, having a normal and healthy copy of the gene decreases the risk of developing breast cancer. The risk only increases if the gene is mutated or abnormal, and therefore does not perform its natural cancer-prevention functions.
- PALB2 – After BRCA1 and BRCA2, PALB2 is currently the third most prevalent breast cancer gene. PALB2 is short for “Partner And Localizer of BRCA2.” In other words, it works in partnership with the BRCA2 gene to repair DNA damage and thereby prevent breast cancer from developing. An estimated 35% of women with a mutated PALB2 gene will develop breast cancer by age 70.
- CHEK2 – “Checkpoint Kinase 2,” or CHEK2, creates a protein that helps suppress tumor growth. Having a mutated CHEK2 gene doubles the risk of breast cancer in women. In men, it makes male breast cancer 10 times more likely to occur.
- CDH1 – CDH1, or “CaDHerin 1,” is a tumor suppression gene that helps groups of cells stick together to form organized tissues. A mutation in the CDH1 gene can increase the risk of forming lobular breast cancer, or cancer that begins in the breast’s milk-producing lobules. Since the gene normally helps cells stick together, a mutation can also make it easier for individual cancer cells to break off from a breast tumor and metastasize, or spread to other parts of the body.
- PTEN – The “Phosphatase and TENsin homolog” (PTEN) gene helps prevent tumor growth by controlling the rate of cell division. It also causes damaged cells to self-destruct before they can become cancerous. Like CDH1, PTEN also plays a role in helping cells stick together, which can help prevent cancer from spreading.
- STK11 – “Serine/Threonine Kinase 11” is another tumor suppressor. STK11 gene mutations cause Peutz-Jeghers syndrome. Peutz-Jeghers syndrome carries an increased risk for multiple types of cancer, including breast cancer.
- TP53 – Also known as P53 (and nicknamed the “guardian of the genome”), “Tumor Protein p53” recognizes when a cell’s DNA has been damaged. It then either activates a DNA repair gene (like BRCA1) or causes the cell to self-destruct. If TP53 is mutated, the damaged DNA won’t be repaired and the cell will live on, perhaps becoming a cancer cell. Though some TP53 mutations are inherited, most of them occur during a person’s lifetime and are only found in cells that become cancerous.
There are a number of other genes, including ATM, BARD1, BRIP1, CASP8, CTLA4, CYP19A1, FGFR2, H19, LSP1, MAP3K1, MRE11A, NBN, RAD51, and TERT, that are thought to also increase the risk of developing breast cancer when they carry a mutation. There is also a rare gene mutation called Cowden Syndrome that links breast cancer, uterine cancer, thyroid cancer, and large head circumference together.
While you cannot change your genetics or family history of breast cancer, knowing that you are at a higher risk can help with creating an early detection plan to detect breast cancer in its earliest stages, while it is still localized (there is no sign that the cancer has spread outside of the breast), and easier to treat.
Some people with a family history of breast cancer may choose to undergo genetic counseling and genetic testing to see if they have inherited genes that increase the risk of the disease. It is also advisable to maintain an accurate family medical history to determine if there is a significant family history of breast cancer or other illnesses.
Medically reviewed June 2023