When a cell grows, it divides, by making copies of its DNA. Sometimes the DNA doesn’t match exactly, and the new cell if different from the original cell. The result is called a mutation.
Some people are born with cell mutations. They are called a genetic, or hereditary, mutation. That means you inherited these mutations from your mother or father. It works like this if one of your parents was born with a mutation in one of their genes, there’s a 50-50 chance they will pass it on to you, or you will inherit it. That’s because they could pass on either their healthy gene or the altered one.
Recent studies are reporting that up to 10% of all breast cancer diagnoses are due to this type of mutation. Mutations named BRCA1 (Breast cancer 1) and BRCA2 (Breast cancer 2) are the most common hereditary mutations. These genes help cells repair mistakes that can happen each time a cell divides and grows. Because BRCA stands for breast cancer, it’s easy to think BRCA mutations only increase breast cancer risk. But that is not true these mutations are actually found in every cell in your body. BRCA mutations also increase the risk for pancreatic cancer, ovarian cancer, prostate cancer, and melanoma (a dangerous type of skin cancer).
Another type of mutation is called an acquired mutation. These types of mutations happen after a person is born. The cell makes a mistake as it copies its DNA when it divides. Generally, there are environmental issues like radiation or chemicals which cause these changes. Cells can build up too many harmful genetic changes, and when these damaged cells survive, they can start to grow and divide faster than they should. When this happens, cancer has begun.
If you have a lump or tumor in your breast, your doctor will test your tumor to see if the tumor’s cells have changes in a gene called HER2. These changes cause the gene to make too much of the HER2 protein. Too much of the HER2 protein makes the tumor HER2-positive. If the HER2 protein is normal or low, it’s classified as HER2-negative.
Reports show up to 20% of breast cancer patients have tumors that test HER2-positive. It is crucial to know because these tumors tend to spread faster than HER2-negative ones and are more likely to come back after treatment. If your cancer is HER2-positive, your doctor can treat it with specific drugs that target and block the HER2 proteins. These targeted therapies can be very successful.
PALB2 is the third most common breast cancer gene after BRCA1 and BRCA2. It works with the BRCA2 gene to repair DNA errors that can happen during cell division. (PALB2 is short for “partner and localizer of BRCA2.”) It is up to 9 times more likely that you’ll get breast cancer if you have an abnormal PALB2 gene.