Breast Cancer Genetic Testing

Do you know which genetic test for breast cancer to order? Test your knowledge in Kayla's case and see the free CME courses and resources below for more information!

Test your knowledge

Kayla Cancer DiagramKayla is 32 years of age and was just diagnosed with breast cancer. Her mother had breast cancer at age 45, and her maternal aunt had breast cancer at age 30. Her maternal grandmother died of ovarian cancer at 54.

You determine that Kayla is at high risk for breast and ovarian cancer, and she is interested in genetic testing.

What is the best genetic testing option for Kayla?

  1. Comprehensive analysis of the BRCA1 and BRCA2 genes
  2. A panel of genes associated with a high risk for hereditary breast cancer
  3. A panel of genes associated with moderately-increased breast cancer risk
  4. No testing

See the answer

The correct answer is C. Yes, her personal and family history is sufficient to refer her to genetics.

In this case, the decision about referral for germline testing is based on MV’s personal and family history, not on the results from tumor testing. MV’s personal history of having two right-sided synchronous colon cancers is suspicious for Lynch syndrome. Furthermore, in this case, her personal and family history of colon, ovarian, and stomach cancers, is significant because these are classic Lynch syndrome component tumors.

It is important to collect sufficient information about the family history in order to assess genetic risk. MV’s family history report does not include who in the family was affected with stomach and ovarian cancers, or at what age they were diagnosed, which can help clarify whether or not MV is truly at risk for a hereditary cancer susceptibility disorder. In addition to identifying the cancer types in the family, ask how the affected individuals are related to your patient (e.g., sister, maternal grandfather, etc.) and the age at which the relative was initially diagnosed with cancer. In this case, it is also important to assess the patient and family for non-cancer risk factors, including the presence of multiple colon polyps over a lifetime. Most pertinent to this case, NCCN recommends that any individual “with colorectal or endometrial cancer and >= 2 first-degree or second-degree relatives* with a Lynch syndrome-related cancer, regardless of age” be evaluated for Lynch syndrome. MV meets this criterion. Furthermore, her personal history of synchronous colon cancers meets NCCN referral criteria alone.

Genomic tumor testing should not be used to diagnose patients with a hereditary cancer syndrome. Tumor-only tests, such as ActionSeq, that assess only the cancer tissue for variants, do not test normal (germline) cells. Tests that assess both tumor and normal tissue (tumor-normal testing) may or may not report variants in the germline. In addition, tumor tests may not report on all variants associated with hereditary cancer syndromes if they are not associated with targeted treatments and/or the test lacks sensitivity to detect the variant. Relevant to MV’s case, at the time it was done, ActionSeq included testing for 4 of the 6 genes associated with Lynch syndrome. Therefore, a negative tumor result (or one that does not include a pathogenic germline variant) reduces but does not rule out this condition.

In some cases, results from genomic tumor testing may help determine which patients should be referred for further evaluation. Results that indicate a pathogenic variant found in a gene associated with a hereditary cancer syndrome that conforms to the patient’s personal or family history (e.g., BRCA1 variant in a woman with ovarian cancer), a known founder mutation (a variant common in individuals in a specific population such as those with Ashkenazi Jewish or French-Canadian descent), or the presence of many variants all warrant further evaluation to determine whether germline testing is appropriate.

In all cases, regardless of genomic tumor testing results, if a patient meets germline testing criteria, he or she should be referred.

* first-degree relatives are parents, children, and siblings; second-degree relatives are half-siblings, grandparents, aunts, uncles, and grandchildren.

Learn more

About one in 10 women has a family history of breast and/or ovarian cancer that puts her at increased risk of developing these malignancies due to underlying genetic factors. These courses provide opportunities to learn about hereditary breast cancer syndromes, how to use family history to assess risk level, genetic testing, using genetic information to inform management, and communicating with patients about genetic risk. Free CME available.

Genetic Testing for Breast Cancer Risk. Self-directed, 15-minute online program about evaluating how well a particular genetic test assesses breast cancer risk (clinical validity) and the potential impact of testing on patient outcomes (clinical utility).

Collecting Family History. Self-directed, 15-minute online program about asking the right questions to elicit enough information to assess family history disease risk.

Identifying Red Flags and Patterns that Increase Risk. Self-directed, 15-minute online program about identifying genetic red flags and patterns in a family medical history that can help determine if a condition has a significant genetic contribution.

Categorizing Cancer Risk. Self-directed, 15-minute online program that provides opportunity to learn and practice how to analyze family histories and classify the patients' risk into average, increased (or moderate), or high risk for cancer.

Using Family History to Inform Management. Self-directed, 15-minute online program about determining appropriate management based on family history risk using available guidelines.

Pre-test Decisions & Counseling. Self-directed, 15-minute online program about deciding when and if genetic testing is appropriate, given the clinical and personal context.

Interpreting Genetic Testing Results. Self-directed, 15-minute online program about interpreting genetic testing results within a patient’s specific context.

Genetic Testing Technology. Self-directed, 15-minute online program about weighing the benefits, risks, and limitations of different tests within specific patient contexts.

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