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. It’s possible that someone you know — or maybe even you — has had it done. Most often, people pursue genetic testing to satisfy curiosity about their ancestry or to connect with relatives from other branches of their family tree.
But genetic testing can also reveal important information about our health, including cancer risk.
“Genetic testing for cancer risk uses a saliva or blood sample to look for changes in specific genes — or pieces of DNA — that are associated with an increased risk of certain types of cancer,” said Erin Linnenbringer, a board-certified genetic counselor and associate professor at Washington University School of Medicine in St. Louis.
There are many genes linked to cancer. Two of the most well-known examples are BRCA1 and BRCA2, Linnenbringer said. 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 face elevated risks, including breast, pancreatic and prostate cancer.
While most gene mutations do not increase cancer risk as significantly as BRCA1 and BRCA2, they can still have an important impact. Knowing about these mutations can help guide risk management. Screening tests and health exams may begin at younger ages and occur more frequently, which can help find a cancer earlier when it’s more treatable. For some cancers, medication, surgery or enhanced screening may even help prevent disease.
Right now, this type of genetic testing is typically ordered through a health care professional and is most often recommended for individuals who have had cancer or who have a strong family history of cancer.
“People diagnosed with adult-onset cancers at a young age — such as breast cancer before age 40 — those with aggressive or late-stage cancers, or those with certain rare cancers, including ovarian or pancreatic cancer, should consider genetic testing,” Linnenbringer said. “The same is true for individuals with multiple relatives on either side of the family who have had cancer, or when a parent or sibling was diagnosed at a young age.”
If you have concerns about your family history and cancer risk, the first step is discussing them with your health care provider. “They may review your family history and order an appropriate genetic test, or refer you to a genetic counselor or specialist,” Linnenbringer said. “You can also search for a counselor near you at findageneticcounselor.nsgc.org.”
Genetic counselors are a valuable resource for thinking through the elements that go into deciding whether genetic testing is right for you. “They are health care professionals with specialized training in genetics as well as patient communication and counseling,” Linnenbringer said. In addition to assessing cancer risk, counselors help patients understand implications of testing that might not immediately come to mind. These may include emotional considerations, potential effects on life insurance, and information relevant to family members who may share similar mutations.
For those uncertain about their family health history, holidays and gatherings can offer opportunities to ask relatives about past diagnoses. Learning which cancers occurred and the ages at diagnosis can provide important clues about inherited risk. While such conversations are not always easy, they can offer valuable insight into whether genetic counseling or testing may be helpful.
Looking ahead, Linnenbringer said the benefits of genetic testing will likely grow as research expands and knowledge deepens.
Dr. Graham A. Colditz, an internationally recognized leader in cancer prevention, leads prevention research at Siteman Cancer Center at Barnes-Jewish Hospital and WashU Medicine in St. Louis