GERMLINE GENETIC TESTING following a cancer diagnosis can help determine a patient’s risk of developing other cancers and assess heightened cancer risk among their immediate family members.

Germline mutations are genetic changes that are inherited from parents and can be passed on to children. Somatic mutations occur in other body cells and are not inherited. Germline tests are recommended by official guidelines for many types of cancer, including ovarian cancer and male breast cancer. But a study published June 8 in JAMA found that just 6.8% of patients diagnosed with cancer in the study population received a test following their cancer diagnosis.

“Single digits for guideline-directed care? I was surprised by that,” says B.J. Rimel, a gynecological oncologist specializing in ovarian, cervical and uterine cancers at Cedars-Sinai Hospital in Los Angeles, who was not part of the study team. For ovarian cancers, for instance, she says, “One hundred percent of people should be tested.”

While more research is necessary to understand why a gap exists between recommendations and clinical practice, the study helps characterize the problem and will guide clinicians and researchers as they try to find solutions—which was one reason the study’s lead author, Stanford University of Medicine oncologist and epidemiologist Allison Kurian, says she began the research in the first place.

“I practice at Stanford, which is an academic center, and certainly we are not representative of the way most people with cancer receive care,” she says, noting the higher level of care usually received at academic cancer centers compared to the average treatment center.

Kurian and her colleagues matched nearly 1.4 million anonymized records of cancer patients diagnosed between 2013 and 2019 drawn from the California and Georgia state cancer registries with germline genetic testing information from four laboratories that performed most of the tests in those states.

“That really gave us the first view that we’ve had in the United States of who’s getting this kind of testing and who’s not,” Kurian says.

Not only were the overall testing rates low, but testing rates for specific cancer types fell far short of guidelines. Only 50% of male breast cancer patients received germline genetic testing, for instance, and only 38.6% of ovarian cancer patients and 26% of female breast cancer patients were tested.

“In male breast cancer, for more than 15 years, national guidelines have said to test every patient. Insurance covers it. There should not be a barrier there,” Kurian says. “The same is true for ovarian cancer. For more than 10 years, the recommendation is to test 100% of patients.”

The study also found significant racial disparities in germline genetic testing. While 31% of white breast cancer patients—male and female—and ovarian cancer patients were tested, only 22% of Asian patients, 25% of Black patients and 23% of Hispanic patients received the testing.

“It was really unfortunate, because it was actually most pronounced for the cancers where guidelines are the strongest,” Kurian says. “We’ve known for years that we need to test these people. And disparities were substantial, and they were not improving at all.”

There are three main reasons why germline genetic testing is important after a cancer diagnosis, the first being that mutations in certain genes can increase your risk of developing additional cancers, according to Kurian. Changes in the BRCA1 and BRCA2 genes are linked not only to a heightened risk of breast cancer, but also ovarian, pancreatic and prostate cancer. Mutations in the multiple genes associated with Lynch syndrome mean a patient with endometrial cancer could have a heightened risk for colon cancer.

Knowing if you carry mutations in certain genes can also help guide oncologists in treating your current cancer, according to Kurian.

“There are new drugs that were not around 10 years ago called PARP inhibitors,” she says. “They are drugs that were specifically designed to be effective in patients with BRCA1 and BRCA2 gene mutations.”

Lastly, because germline mutations are changes in the genetic code that a person is born with, they can be inherited and so could affect a patient’s children, siblings, parents and grandparents. “If you have something, your family member could have it, and we can protect them from getting cancer and dying from it,” Kurian says.

The study did not dig into the reasons why patients were not receiving genetic testing after their diagnosis, but Kurian has been involved in past surveys of patients that have suggested physicians often don’t offer the tests to their patients.

“I thought the number one reason would be money,” she says, “but it wasn’t. It was, ‘My doctor didn’t recommend it.’”

It’s asking a lot of cancer patients, families and caregivers, Rimel acknowledges, but genetic testing is one area where it pays to be proactive and ask about testing if the physician doesn’t bring it up first.

“The best process is where you see a genetic counselor, they take your family history, they look at your tumor history, they talk to you and they say, ‘OK, this is the test that encompasses the genes that you need most,’” Rimel says. “Ideally, their physician has access to [genetic counseling], but most health insurance providers, like Blue Cross Blue Shield, have genetic counseling through their websites.”

Jon Kelvey is a freelance writer covering health and science. He lives in Maryland.