Breast Cancer and Ovarian Cancer
What is breast cancer and ovarian cancer?
Cells normally grow and divide just enough to grow or to replace damaged tissue. But sometimes the mechanisms that regulate cell growth stop working and cells divide out of control. This out-of-control growth is called cancer. Cancer that develops in breast or ovarian tissue is called breast or ovarian cancer, respectively.
Most people who develop breast or ovarian cancer have no history of the disease in their family. In fact, only 5 to 10 percent of all breast and ovarian cancers are caused by inherited genetic factors. These rare cases typically result from inherited mutations in either the BRCA1 or BRCA2 gene.
BRCA1 and BRCA2 are called tumor suppressor genes, because they control cell growth. BRCA1 is located on chromosome 17, and BRCA2 on chromosome 13. Scientists believe BRCA1 and BRCA2 work by fixing damaged or broken DNA. Women who inherit a mutated copy of the BRCA1 or BRCA2 gene accumulate broken and deformed chromosomes, and therefore have a greater chance of accumulating mutations that will lead to uncontrolled cell growth and cancer. Men who inherit the defective genes are also more likely to develop breast and/or prostrate cancer. (Yes, men can get breast cancer.)
How do people get breast or ovarian cancer?
High-risk families include those whose members carry a mutation in either the BRCA1 or BRCA2 gene. The mutated BRCA1 and BRCA2 genes are inherited in an autosomal dominant pattern. A child needs to inherit just one copy of the mutated gene to have an increased cancer risk. Children who have a parent with a BRCA1 or BRCA2 mutation have a 1 in 2 chance of inheriting the mutation.
Just because a person inherits the defective gene does not mean he or she will develop cancer, but inheritance greatly increases the risk. Out of every 100 women who inherit a mutated BRCA1 or BRCA2 gene, as many as 60 will develop breast cancer by age 50; by age 70, approximately 80 will develop breast cancer.
How do doctors test for BRCA1 and BRCA2 mutations?
A person with a strong family history of breast or ovarian cancer is a candidate for genetic screening. By analyzing a sample of the patient's blood, doctors can identify whether the person has inherited a BRCA1 or BRCA2 mutation. The test cannot tell if or when the person will develop breast or ovarian cancer; it can only tell if he or she is at risk because of the faulty gene.
What can a woman do if she inherits these mutations?
Some women who discover that they've inherited a mutated BRCA1 or BRCA2 gene undergo special treatments to protect themselves from breast and ovarian cancer. They can start having mammograms at a younger age to screen for abnormal cell growth in the breasts (most women start having mammograms at age 40).
They may choose to have their breasts and/or ovaries removed, even before cancer begins. And they may take the medicine tamoxifen, which is believed to protect against breast cancer.
Interesting facts about breast and ovarian cancer
The progression from a benign to a malignant cancer typically requires multiple mutations that allow cells to acquire new and abnormal characteristics, such as an increased growth rate, inability to adhere or stick to neighboring cells, propensity to migrate to other places in the body, etc. Genes involved in the repair of DNA damage (such as BRCA1 and BRCA2) are often associated with cancer. This is because they allow mutations to accumulate at a much faster rate.
Usually, people inherit one of several hundred different mutations of the BRCA1 and BRCA2 genes. But for some reason, Eastern European (Ashkenazi) Jews seem to inherit only three of these different mutations. Ashkenazi Jews are also 10 times more likely to have mutations in the BRCA1 and BRCA2 genes than any other ethnic group.