Breast cancer is the most common cancer among women of all races. About 1 in 8 American women will develop breast cancer in her life. In certain families the risk is much greater than average.
Other cancers (ovarian and colorectal, for example) also seem to occur at higher rates in certain families. Sometimes a defective gene (the genetic material that parents pass to their children at the moment of conception) carries this higher-than-normal cancer risk down through generations in a family. Heredity probably causes only about 5 to 10 percent of all cancers. But knowing whether your family carries a family cancer syndrome may affect your doctor’s recommendations and the decisions you make about your healthcare.
What do you need to know about family cancer syndromes?
Even when a family seems to experience cancer more frequently than most families, the cause is not always hereditary. Non-genetic risk factors sometimes run in families—like cigarette smoking, obesity, exposure to a toxin (harmful chemical) in the home environment, etc. Some families have been afflicted with an unusual number of cancers purely by chance.
Keeping your doctor informed about changes in your family medical history is an important part of preventive healthcare. Women should be especially alert to:
- Cancers among family members that occurred at a young age (like breast cancer before menopause)
- More than one kind of cancer in the same family member (Has one relative had both breast and ovarian cancer?)
- A cancer that has been found in both breasts
- A male family member with breast cancer
A close relative with cancer (a parent, brother, or sister) causes greater concern than a more distant relative. Having more than one relative with the same or a related cancer on the same side of your family is more significant than having two relatives with cancer who are not related to each other.
Hereditary Breast and Ovarian Cancer
We now know that, if a woman carries a defect (a mutation) in either of two genes, BRCA 1 and BRCA 2, her risk for developing breast or ovarian cancer may be as high as 45 to 80 percent. This gene can pass from one generation to the next on either the mother or father’s side of the family. Furthermore, because the risk of breast or ovarian cancer seems to run in other families where no BRCA 1 or 2 gene defect can be found, scientists now believe that a third gene related to these cancers will be identified in the future. The defective genes can also cause cancer of the fallopian tube, primary peritoneal cancer, pancreatic cancer, male breast cancer, and prostate cancer.
This is the most common hereditary syndrome that increases the risk for colon cancer within families. People with Lynch syndrome have a very high risk of developing colon cancer and typically develop it at a young age—before 50. Women with Lynch syndrome also have a high risk of developing endometrial cancer (cancer of the lining of the uterus). Certain other cancers are also linked to Lynch syndrome including cancer of the ovary, stomach, small intestine, pancreas, kidney, brain, ureters, and bile duct.
Defects in the BRCA1, BRCA 2, and genes associated with Lynch syndrome can be identified through genetic testing using a blood sample. Your personal and family medical history determines whether you would benefit from genetic testing. It is important to update your doctor about any changes in your family medical history at your annual well-woman exam.
If your family cancer history suggests that you would benefit from genetic testing, we will discuss this option with you. Finding that you have a genetic risk for a specific type of cancer will affect our recommendations for your future healthcare. We may recommend that you begin screening exams at a younger age, consider additional testing, and/or refer you to a breast or colorectal cancer specialist. We will also help you to understand how the results of genetic testing may impact other family members.
Best Wishes for a healthy fall!