By Dr. Graham A. Colditz

Siteman Cancer Center

Of the many advances in science and technology over the past 25 years, genetic testing is arguably one of the most notable. Once a rare part of health care, it is now becoming much more common. And it’s possible that someone you know — or maybe even you — has had it done. Most often, people get genetic testing to settle curiosity about which parts of the world their ancestors may have come from or to connect with relatives from other branches of their family tree.

But genetic testing can also reveal important information about our health, including the risk of cancer.

“Genetic testing for cancer risk uses a saliva sample or blood sample to look for changes in specific genes — or pieces of DNA — that are associated with increased risk of certain types of cancers,” said Erin Linnenbringer, a board-certified genetic counselor and associate professor at Washington University School of Medicine in St. Louis.

There are many genes that are related to cancer. Two of the most well-known examples are BRCA1 and BRCA2, Linnenbringer added. Women with harmful changes — known as “variants” or “mutations” — in these genes have a much greater risk of developing breast, ovarian and pancreatic cancer. Men with these mutations also have a greater risk of breast and pancreatic cancer as well as prostate cancer.

While most gene mutations don’t increase cancer risk as much as those in BRCA1 and BRCA2 can, they can still have an important impact. And knowing that can help with managing the increased risk from a mutation. Screening tests or regular health exams can begin at younger ages and be done more often, which can help find a cancer earlier when it’s more treatable. And, for some types of cancer, medication, surgery or screening can even help prevent the disease.

Right now, this type of genetic testing is typically ordered through a health-care professional and is done in people who have had cancer or have a strong family history of cancer.

“People who are diagnosed with an adult-onset cancer at a young age, such as having breast cancer before the age of 40, who have been diagnosed with an aggressive or late-stage cancer, or who have certain types of rare cancers, like ovarian cancer or pancreatic cancer, should consider having genetic testing,” Linnenbringer said. “The same is true if you have more than one relative on your mom or dad’s side of the family who has had cancer, or if your parent, brother or sister was diagnosed with cancer at a young age.”

If you have concerns about your family history and cancer risk, the first step is often sharing that with your health-care provider. “They may be comfortable reviewing your family history and ordering an appropriate genetic test, or they may refer you to a genetic counselor or other specialist,” Linnenbringer said. “You can also search for a counselor near you, at findageneticcounselor.nsgc.org.”

Genetic counselors are a great resource for thinking through the elements that go into deciding if genetic testing is right for you. “They are health-care professionals with specialized training in both genetics and patient communication and counseling,” Linnenbringer said. In addition to assessing cancer risk from your personal and family history, genetic counselors can also help with considering the implications of testing that might not immediately come to mind. This can include its possible effect on life insurance and emotional health, as well as other family members — who may have the same mutations that your testing could find.

If you don’t have a good idea of your family health history, the upcoming holidays can be a fantastic opportunity to connect with family members and get more details. Try to find out the types of cancer any relatives may have had, and around what age they were diagnosed. It can also be helpful to know if any have had genetic testing. This may not always be the easiest conversation, but it can be worth the effort — providing valuable information about whether genetic counseling or genetic testing may make sense.

Looking to the future, Linnenbringer feels the benefits of genetic testing will likely only increase as we learn more through continued research and expanded testing across a wider range of people.

Dr. Graham A. Colditz, associate director of prevention and control at Siteman Cancer Center at Barnes-Jewish Hospital and WashU Medicine in St. Louis, is an internationally recognized leader in cancer prevention and the creator of the 8ightWays® to Prevent Cancer series.