You can thank your parents for your great cheekbones and a full head of hair, but in those genes they may also have passed on a mutation that can lead to a higher risk of certain diseases including cancer. How do you know if you are a candidate for genetic testing?
The Link Between Genes & Cancer
People inherit two sets of most genes, one from each parent. The Human Genome Project estimates that people have between 20,000 and 25,000 genes. The National Institutes of Health reports that the majority of genes are the same between people, with slight differences to a small number of genes that account for different physical features. When a gene mutates, it cannot grow normal, healthy cells and genetic diseases occur, as in the case of hereditary cancers according to the National Cancer Institute.
“With advancements in medicine, we now know more about the relationship between gene mutations and cancer risk. If you or your family members have cancer, you and your family members may have gene mutation inherited from parents,” said Vicky Lee, MD, from Samaritan Hematology & Oncology Consultants who provides genetic counseling services. “Once we know if you have a mutation, then we can take steps to prevent cancer by close clinical surveillance, surgery or chemoprevention.”
Different gene mutations cause different cancers. Certain gene mutations may increase the cancer risk up to 80% and others may increase 3% to 5%, depending on different mutations.
How Does Testing Help?
There are about 50 cancer syndromes that have been linked to various gene mutations, says Dr. Lee. Some of the well-known mutations include the BRCA1 and BRACA2 mutation that are related to hereditary female breast and ovarian cancer syndrome. Lynch Syndrome is also common and related to cancer in the colon and rectum
“The type of cancer and risk of cancer caused by certain gene mutations are very specific,” said Dr. Lee. “We encourage people who have personal history of cancer or family members with cancer to talk to their doctor to see if they would benefit from cancer genetic counseling.”
Once you are tested, knowing you have the gene mutation can help you take precautions. For example, some women who test positive for the BRCA1 and BRCA2 mutations may choose to have surgery to remove the breast and ovarian tissue to prevent cancer from developing. Your physician may also recommend preventive screenings more often if you have a higher risk of hereditary cancer.
When Should You Be Tested?
When deciding whether you should be tested, it helps to look at the health history of your family members, including at least three generations — grandparents, parents, siblings and children. The National Cancer Institute gives risk factors for a hereditary cancer as:
- Two or more family members with tumors of the same site.
- Two or more family members with tumor types belonging to a known familial cancer syndrome.
- Two or more family members with rare tumors.
- Three or more relatives in two generations with tumors of the same site or related sites.
- One family member diagnosed with cancer that has:
- Multiple tumors
- Tumors in both organs that are a pair, e.g. kidneys, lungs
- Younger-than-usual age at diagnosis
- Rare tumors
“We’re paying more attention to cancer and genetics now because we’ve discovered that by knowing the mutation, certain cancers can be prevented,” said Dr. Lee. Dr. Lee likes the quote from Mary-Claire King, PhD, “To identify a woman as a carrier only after she develops cancer is a failure of cancer prevention.”
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