How genetic testing impacts the whole family

Genetic testing can be an important way to learn more about why cancer developed and how best to treat it.

“Germline” testing is an analysis of your DNA for genetic mutations and alterations that were passed down from your family members.

Whether you are newly diagnosed, have started treatment, or even finished your cancer care, knowing if inherited genetic mutations played a role in your cancer can inform both your future and your family’s.

Steven J. Katz, M.D., M.P.H., professor of general medicine and of health management and policy at the University of Michigan, has studied how people with cancer make treatment decisions.

He and his colleagues at U-M and Stanford University are in the middle of a federally funded research study to understand how people with cancer are engaging with genetic testing and to improve how they share test results with their families.

Here are key takeaways from this research about the benefits of genetic testing for people with cancer and family members who may be predisposed due to genetic risks.

Why should some people with cancer consider genetic counseling?

Only about 15% of patients who undergo genetic testing have a finding that warrants formal genetic counseling.

Genetic counseling is best reserved for these instances and particularly for patients with clinically meaningful results – that is, a mutation that may inform decisions about treatment or cancer prevention strategies for the patient but as importantly have implications for cancer risk in the family.

Because most patients have negative or non-contributory findings, there is growing consensus that most patients can undergo genetic testing and discuss results through their cancer doctors.

Guidelines for testing are expanding rapidly and there are not enough genetic counselors to engage patients before testing.

How are the results used to guide treatment? Is there always an impact?

Results of germline genetic testing after a cancer diagnosis generally do not inform treatment decisions for the diagnosed cancer, although sometimes it can indicate a specific treatment.

One important example is that people with breast cancer who have a BRCA mutation may be candidates for a new oral treatment called PARP inhibitors that can improve survival.

About 5% of patients with breast cancer may carry a BRCA mutation.

Many more patients benefit from genetic testing because results inform risk of future cancers for themselves and their family.

Patients and families with hereditary cancer syndromes can lower cancer risk through prevention and early detection.

Already, guidelines recommend testing all patients diagnosed with ovarian cancer and male breast cancer.

Guidelines are expanding to include patients with pancreatic cancer and many more women diagnosed with breast cancer.

Is there benefit to seeking out genetic testing and counseling after completing treatment?

Yes. While more people are getting tested at the time of a cancer diagnosis, most do not.

We're recognizing that survivors of cancer need to continue to follow-up closely with their cancer doctors.

Many get active treatment for years (think endocrine therapy for breast cancer) and need surveillance, including detection of new cancers.

Genetic testing in survivorship is extremely important because it can inform prevention and early detection strategies to reduce the risk of cancer over the life course.

Also, test results have important implications for cancer risk in families.

A patient with a clinically meaningful mutation can trigger testing in relatives—called cascade testing—that can reduce the burden of cancer in families through prevention and early detection.

Why should people notify family members of genetic testing results?

If a patient is found to have an inherited risk of cancer, telling relatives gives family members the power of knowledge.

Testing relatives identifies cancer risk that can be addressed through prevention and early detection.

Relatives who learn they don’t have the inherited risk can be reassured that they are not predisposed.

The good news is that our research shows virtually all patients with cancer in whom a clinically meaningful mutation is revealed share their results with most family members.

Patients recognize their results are very important and useful to their relatives.

Which family members should patients notify?

All first-degree and second-degree relatives have substantial risk of carrying the pathogenic variant revealed in a patient’s test result.

This includes parents, children and siblings, as well as grandparents, grandchildren, aunts, uncles, nieces, nephews and half-siblings.

What are you learning in your research about the use of genetic counseling and how results are shared with families?

We find that patients do share their results with most first-degree relatives and many second-degree relatives.

But we are concerned there is too little clinical and professional support for patients to communicate effectively about the implications of genetic test results and potential next steps, including education, cascade testing and follow up.

Barriers include limited genetic counselor resources, insurance-related barriers (patients’ insurance does not cover services to family members), the complexity of communicating about genetics, and the challenges of communication in families.

There is enormous need to develop tools and strategies to engage families with hereditary cancer syndromes.

We at the University Michigan and Stanford aim to close the gap in cascade risk evaluation to reduce the burden of cancer in these families and in the United States overall.

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