I survived cancer, so why do I need genetic testing for it?

As As a clinical genetic counselor, I saw many cancer survivors for genetic counseling. In some cases, it had been 30-40 years since they were diagnosed. Some of them were in their 60s-70s when I saw them, but they were young at the time of their cancer diagnosis. Years later, they were referred to me to talk about the possibility that their history of early-onset cancer was related to a gene mutation. Common questions they asked me were, “Well I already had cancer, what good is genetic testing now?” or, “Why am I here? I already had genetic testing when I was diagnosed 15 years ago.” My answers often focused on the fact that even if you had cancer in the past, genetic counseling to discuss genetic testing was still important for many reasons, even years later. I want to take some time to share some of those reasons with you today, just in case you or someone you know is a cancer survivor who isn’t sure if genetic testing could be helpful:

  1. Reducing your risk for another cancer – In most cases, a person with a gene mutation related to hereditary cancer is at an increased risk for more than one type of cancer, and may also have a higher risk of getting the same type of cancer again. For example, someone with a BRCA1 or BRCA2 mutation has an increased risk for ovarian cancer,pancreatic cancer, and melanoma. If you are a woman with a BRCA1/2 mutation that has already had breast cancer,you have a much higher chance of developing another (separate) breast cancer. Genetic testing is helpful, because knowing if you are at an increased risk for another cancer can help your doctors make a plan and discuss cancer screening and/or prevention options with you. This would include increased breast cancer screening and removing your ovaries to reduce the risk for ovarian cancer.
  2. Providing information to your family members – If you test positive for a genetic mutation, your relatives could carry it as well, which means that they also could have a significantly increased risk for certain cancers. For example, your children and siblings could have up to a 50% chance of having inherited the same mutation. Based on this, your adult family members can be tested to find out if they also carry the mutation. Many of them may have the opportunity to be tested before they ever get diagnosed with cancer. This information could help them prevent developing a future cancer, or increase the chances that any cancer would be found early through screening (when it is usually more treatable).
  3. Testing options change over time – The field of cancer genetics changes very quickly, which means that even if you tested negative in the past, you may still want to talk to your doctor about the possibility of new or updated genetic testing. For example, if you had BRCA1/2 genetic testing 10-15 years ago, there may be additional testing available now that you might want to learn about and consider. We have also learned a lot about other genes that are linked to hereditary breast and ovarian cancer (and other types of hereditary cancer). There may be testing available for you of genes that weren’t even known about at the time that you were first diagnosed or had testing. So just in case, it can’t hurt to ask your doctor if you should reconsider the option of genetic testing.
  4. Finding the answer – One additional potential benefit of genetic testing for survivors (or for someone with cancer), which I learned about from my patients, is that it can be emotionally beneficial to find the answer as to why you had cancer in the past. It can also be empowering to know that you have the ability to help not only yourself, but also your family members, by learning more about the possibility of hereditary cancer. 

As you can see, even if you had cancer many years ago, talking to your healthcare provider about genetic testing may still be important and helpful for you and your family. Being a cancer survivor does not always mean you need to consider genetic testing, but if you had cancer at a young age and/or have a family history of cancer, or if you aren’t sure if this option would be right for you, talk to your healthcare provider to find out more information. 



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