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It Is All About Breast Cancer


The Genetics of Breast Cancer

You've probably heard or read about breast cancer genes (BRCA1 and
BRCA2). All of us have BRCA1 and BRCA2 genes. These genes are
thought to be tumor suppressor genes. They can lead to breast and ovarian
cancer when you inherit them in a mutated form. The mutation interferes
with the genes' ability to put the brakes on cell growth.


Figuring out the chances of inheriting a mutated BRCA1 or BRCA2 gene can be
mind-boggling, which is why it's a good idea to talk with a counselor, doctor, or
nurse who is trained in cancer genetics. We'll talk about one example here. If a
mother or father carries a mutated copy of one of these genes, each child has a 50 percent chance of inheriting either the normal copy of the gene or the abnormal copy. If the child inherits an abnormal BRCA1 or BRCA2 gene, the child has a higher chance of getting breast or ovarian cancer, or both, than the child who has normal copies of these genes. Men who have a mutated BRCA1 gene do not have a higher risk of getting breast cancer but may have a higher chance of getting prostate cancer than do men who do not have this gene mutation. Men who have a mutation in BRCA2 have a 5 to 10 percent risk of getting breast cancer. Both men and women who have a BRCA1 mutation may have a slightly higher risk of getting colon cancer than people who have normal BRCA1 genes. Another gene that contributes to breast cancer in young women is called p53. A p53 mutation is responsible for only about one percent of all breast cancer.

You may have heard about a rare syndrome associated with the p53 gene called the Li-Fraumeni Syndrome (LFS). LFS is characterized by childhood sarcomas (soft-tissue cancers), breast cancers, brain tumors, leukemias, lymphomas, and adreno-corticoid tumors. Because this syndrome is so rare, you should talk to a counselor, doctor, or nurse if you have questions about it. Your blood can be tested to see if oyu have a mutation in BRCAI or BRCA2. Several laboratories we know about do this test. We've listed their addresses at the end of this section. The tests are expensive; they cost between $350 and $2,400 depending on what needs to be done for you.