Genetic Testing in Oncology: Making It Make Sense

February 2018 Vol 9, No 2

Oncology navigators should be educated on the importance of genetic testing in the lives of patients and their families, according to Leigha Senter-Jamieson, MS, LGC, and Associate Professor at The Ohio State University, Columbus, OH.

At the Academy of Oncology Nurse & Patient Navigators (AONN+) 8th Annual Navigation & Survivorship Conference, she gave audience members a rundown on the ever-evolving landscape of cancer genetics and genomics and informed navigators how best to broach the subject with their patients while still prioritizing their treatment preferences.

Most Cancers Are Not Inherited

Most cancers fall into the sporadic category. Only 5% to 10% of cancers fall into the truly hereditary category, whereas 15% to 20% are familial. “But genetics is important for any person with a cancer diagnosis,” said Ms Senter-Jamieson. “Although it took a while for the genetic testing landscape to change, it is now changing very rapidly, and as care providers, we need to think about the patient’s priorities.”

Sometimes the patient’s priority lies in clarifying their future cancer risk; other times he or she wants to determine therapeutic options (ie, the selection of chemotherapeutic agents, avoidance of radiation therapy if necessary, and clinical trial eligibility). Another common motivator is identifying familial risk to initiate cascade testing (testing family members for a mutation already identified in the family), and develop a personalized management plan for at-risk relatives. These plans can include early detection/risk reduction and possible prophylactic strategies, as well as incorporation of a potential chemo­therapeutic approach. “It’s in that setting that we have the opportunity to help our patients and their families actually prevent cancer,” she said.

Biology 101 Refresher: Germline versus Somatic

“Sometimes it can be confusing for us to talk to our patients about the different kinds of genetic testing that can have completely opposite test results,” Ms Senter-Jamieson noted. “But it’s important that we keep this straight.”

A germline mutation—a mutation in a reproductive cell that is transmitted to every cell in the offspring—is referred to as “hereditary” or “inherited” and can be detected in healthy people with a genetic predisposition to cancer. But somatic mutations occur after conception (in cancer, this usually occurs in the tumor cells), and cells that are derived from cells with that mutation also have the mutation.

A person can have a negative germline (blood) genetic test result but still have a mutation in his or her tumor. “This is important to keep in mind, particularly when you’re following a patient for a number of years,” she said. “Just because they have genetic testing at one point in time doesn’t mean it’s the only time you should talk about genetics.”

“Keep This List in Your Pocket”

“This list is not all inclusive, but there are certain cancers that, in and of themselves, warrant a discussion about hereditary cancer,” Ms Senter-Jamieson said. “Without asking any questions at all about family history, if you see a patient with one of these cancers with these characteristics, you should be thinking about genetics.”

These relatively common single diagnoses that warrant a genetics risk assessment or testing include:

  • Breast cancer diagnosed at age ≤50 years
  • Triple-negative breast cancer diagnosed at age <60 years
  • Male breast cancer
  • Colon cancer at age <50 years
  • Endometrial cancer at age <50 years
  • Diffuse gastric cancer at age <40 years
  • All epithelial ovarian cancers
  • All medullary thyroid cancers

The Question of Timing

In regard to the ideal timing of genetic testing, there is no uniform recommendation. It sometimes coincides with consideration of targeted therapy, but because germ­line results won’t change, waiting isn’t necessary, Ms Senter-Jamieson said.

“We don’t have a good script. We have different opportunities to engage patients in genetic testing, but you don’t have to wait for a recurrence to talk about genetics,” she advised. “Whenever you can engage the person, or if they show an interest, it’s a good opportunity.”

If previous testing was done, ask yourself if more testing is warranted, she added, and pay attention to the burden of the patient’s diagnosis. Is this something the patient can deal with right now? The flipside of that is considering the prognosis and determining whether the patient has the luxury of waiting.

Make Genetics Part of Your Routine

Talk about genetic testing with your patients and their providers, she urged. Print a pocket-sized list of the cancers that warrant a serious discussion, regardless of family history. Collect a 3-generation family history and submit this on behalf of your patients to your genetics center, as this will save patients from having to do it.

Set up a mechanism for referral to genetic testing (find a genetic counselor at www.nsgc.org), and talk about cascade testing. “Know the process you’d recommend for your patients,” she added.

According to Ms Senter-Jamieson, the only way to prevent cancer in high-risk families is to arm family members with the knowledge they need to take steps toward risk management. Help patients to have these discussions with their family members, and have the mechanism in place to facilitate those family members getting tested.

“We’re all in the business of taking care of patients with cancer, but we also have the opportunity to prevent cancer by talking about genetics,” Ms Senter-Jamieson said. “So when you’re testing family members, you’re giving your patients a gift.”

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Last modified: June 6, 2018

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