How Genetics Affect Your Cancer Risk
If multiple members of your immediate family have developed cancer of any kind, you might be wondering about your own cancer risk. But while it is possible to have cancer even without a family history of the disease, there is such a thing as inherited cancer syndrome.
Also known as “inherited cancers,” these diseases run in families and are the result of certain genes passed down through the generations. Non-genetic factors, including environmental influences, age, and overall health, also play a role in determining your cancer risk.
What Is Inherited Cancer?
According to the American Cancer Society, 1 in 3 Americans will develop cancer during their lifetime. Since cancer is a fairly common disease, it’s likely numerous members of the same family could develop it at some point. This does not mean that the cancer is hereditary, however. It could be that other factors, such as smoking or poor diet, are common in the family, and that these are the causes of the cancers.
That said, it is possible for family members to inherit an abnormal gene - one that could lead to cancer - that gets passed from generation to generation. This is what is known as inherited cancer. It’s a relatively rare phenomenon - according to the science, only 5% to 10% of all cancers are understood to be linked to inherited gene abnormalities.
Signs that your family might have an inherited cancer gene include many family members with the same type of cancer (especially if it’s a rare type of cancer), cancers occurring at younger ages than usual within the family, and cancer occurring in many generations (grandmother, mother, daughter, etc.).
If you think your family might suffer from inherited cancer, you should speak with your health care professionals to explore options for testing and next steps.
Common Types of Inherited Cancers
Likely the most well-known type of inherited cancer is hereditary breast and ovarian cancer syndrome (HBOC). This is often caused by a mutation in either the BRCA1 gene or the BRCA2 gene, which is then passed on among the generations. In families where this mutated gene is inherited, women will often develop these cancers at much younger age than women without the inherited gene. Women who know there is a strong family history of breast and ovarian cancer might opt for genetic counseling to determine their risk.
Other examples of more common family cancer syndromes are Lynch syndrome, which leads to a higher risk of colorectal, stomach, kidney, and other cancers, and Li-Fraumeni syndrome, which leads to a higher risk of leukemia and other cancers.
Non-Genetic Risk Factors for Cancer
Current science estimates only 5% - 10% of cancers are the result of family cancer syndrome. The large majority of cancers develop as a result of other factors, including environmental and lifestyle factors. Your risk of developing non-genetic cancer could be higher as a result of:
- Age - the risk of developing cancer increases as we get older
- Sex - certain cancers are more common in men than women, and vice versa
- Race - certain cancers are more common in one race as compared to others
- Being overweight or obese
- Excessive alcohol intake
- Lack of physical activity
As with so many diseases, maintaining a healthy diet, regular physical activity, and avoiding smoking and alcohol are ways a doctor might advise you to lower your risk of developing cancer.
Should You Get DNA Testing to Determine Cancer Risk?
If you’re concerned about any of your risk factors for cancer, including family history, you should bring up this concern to your health care professionals. They can advise you on how to minimize your risk, and might refer you to a genetic counselor for testing, especially if there is a suspicion of family cancer syndrome.
If you’ve already taken an at-home DNA test and found results that suggest a genetic risk for certain cancers, bring those results to your doctor to discuss additional testing options and any needed next steps.
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