Multi-Gene Genetic Tests Don’t Cause More Worry Than BRCA Testing Alone in Women Diagnosed With Breast Cancer

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While the results from newer, panel genetic tests looking at a dozen or more genes can be more complex, these results are not causing women diagnosed with breast cancer more worry than older genetic tests that look at only one or two genes.

The research was published online on Dec. 19, 2018, by the journal JCO Precision Oncology. Read the abstract of “Association of Germline Genetic Test Type and Results With Patient Cancer Worry After Diagnosis of Breast Cancer.”

What is hereditary breast cancer?

About 5% to 10% of breast cancers are thought to be hereditary, caused by genetic mutations passed from parent to child. Three of the most well-known genes that can mutate and raise the risk of breast and/or ovarian cancer are BRCA1, BRCA2, and PALB2. Women who inherit a mutation, or abnormal change, in any of these genes — from their mothers or their fathers — have a much higher-than-average risk of developing breast cancer and/or ovarian cancer. Men with these mutations have an increased risk of breast cancer, especially if the BRCA2 gene is affected, and possibly of prostate cancer. Many inherited cases of breast cancer have been associated with mutations in these three genes.

You are substantially more likely to have a genetic mutation linked to breast cancer if:

  • you have blood relatives (grandmothers, mother, sisters, aunts) on either your mother's or father's side of the family who had breast cancer diagnosed before age 50
  • there is both breast and ovarian cancer on the same side of the family or in a single individual
  • you have a relative(s) with triple-negative breast cancer
  • there are other cancers in your family in addition to breast, such as prostate, melanoma, pancreatic, stomach, uterine, thyroid, colon, and/or sarcoma
  • women in your family have had cancer in both breasts
  • you are of Ashkenazi Jewish (Eastern European) heritage
  • you are African American and have been diagnosed with breast cancer at age 35 or younger
  • a man in your family has had breast cancer
  • there is a known genetic mutation linked to breast cancer in your family

Types of genetic tests

When it started about 20 years ago, genetic testing for breast cancer looked at only the BRCA1 and BRCA2 genes. Since that time, genetic testing technology has advanced rapidly, allowing multiple genes to be tested at the same time. These multi-gene genetic tests are called panel tests. Some panel tests look at up to 80 genes in one test.

Because more genes are tested, it’s more likely that a panel test will find a genetic mutation or variant of unknown significance. A variant of unknown significance means part of the gene looks different from the way it’s normally expected to look. However, researchers haven’t confirmed whether this change is harmless or a risk factor for cancer. The variant remains on a watch list, and researchers collect information to figure out if people who have the variant have a higher risk of cancer.

Because of the higher likelihood of a variant of unknown significance result with panel tests, researchers wanted to know if panel genetic testing was causing more worry about recurrence (the cancer coming back) in women diagnosed with breast cancer compared to older genetic tests that looked at only one or two genes.

How this study was done

As part of the iCanCare study, the researchers sent surveys to 7,303 women aged 20 to 79 who were diagnosed with stage 0 to stage II breast cancer between 2013 and 2015. The women lived in Georgia and Los Angeles County.

The survey asked about the women’s demographic information, as well as information related to their breast cancer diagnosis, including treatments and whether genetic testing was done. It also asked how much the women worried about their risk of breast cancer recurrence and how much this worrying affected their lives.

For this study, the researchers looked at the survey responses of 1,063 women, all of whom had genetic testing and genetic counseling:

  • 640 women had a genetic test that looked only at the BRCA1 and BRCA2 gene.
  • 423 women had a panel test that looked at multiple genes.

Overall, the type of genetic test the women had or the results of the genetic test did not influence how much worry about breast cancer affected the women.

Women who:

  • were younger
  • had a lower education level
  • were an ethnic minority

were more likely to worry about cancer to the extent that it affected their lives.

"Genetic testing is becoming increasingly more complex, but increasingly more precise," said study lead author Steven Katz, M.D., MPH, professor of general medicine and of health management and policy at the University of Michigan. "This has led to some ambiguity in test results. The challenge is incorporating this information into the treatment decision without causing unnecessary worry."

"These findings are reassuring," Katz continued. "We found that patients did not overreact whether they got the newer panel testing or BRCA-only testing, and they did not overreact to the test results. Their future cancer worry was not different whether they had a negative test or variant of unknown significance."

What this means for you

If you’ve been diagnosed with breast cancer, you may want to talk to your doctor or a licensed certified genetic counselor about your diagnosis and your family history and ask if having a multi-gene panel test makes sense for you. A licensed certified genetic counselor or your doctor can help you understand the test and accurately interpret the results, helping to ease any concerns you have if the results include a variant of unknown significance.

For more information on genetic testing, including types of genetic tests and how results are reported, visit the Breastcancer.org Genetic Testing pages.

For more information on genes and genetic mutations linked to breast cancer, as well as all the risk-lowering steps you can take if you have a genetic mutation, visit the Breast Cancer Risk Factors: Genetics page in the Breastcancer.org Lower Your Risk section.

To discuss high breast cancer risk with others, join the Breastcancer.org Discussion Board forum High Risk of Breast Cancer. If you've tested positive for a breast cancer mutation and would like to talk about this with others, join the forum Positive Genetic Test Results.

Written by: Jamie DePolo, senior editor

Reviewed by: Brian Wojciechowski, M.D., medical adviser


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