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Genetic Testing Is Beneficial for All Breast Cancer Patients, Study Finds

Scientist with tubes of blood in research lab.

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Key Takeaways

  • A collaborative study by the Mayo Clinic and Invitae found that many breast cancer patients miss out on genetic testing and the opportunity for more precise treatment.  
  • Genetic testing is underutilized in breast cancer patients because it's coupled with complex guidelines. 
  • Mayo Clinic is working through the necessary steps to ensure that any cancer patient receiving care at a Mayo Clinic Cancer Center will receive a comprehensive genomic evaluation in 2021.

A joint study by the Invitae Corporation and the Mayo Clinic concluded that many breast cancer patients do not receive genetic testing and therefore miss out on its benefits, such as the potential to expand treatment options.

The study, called INTERCEPT, was presented at the 2020 San Antonio Breast Cancer Symposium in December.

Over a two-year period, the researchers offered genetic testing to 3,000 patients living with different types of cancer. The researchers found that:

  • 1 in 8 breast cancer patients has genetic variants that increase their risk of more aggressive disease, such as triple-negative breast cancer. 
  • Nearly a third of cancer patients in the study had their cancer treatment modified based on the genetic variants revealed by testing.
  • Half of the patients with genetic variants would not have qualified for genetic testing using current guidelines. 

“For a patient, knowing about a genetic risk factor can help with prognosis and treatment choice, as it may indicate a patient is more likely to face more aggressive or bilateral disease," Robert Nussbaum, MD, chief medical officer of Invitae, tells Verywell. "The patient may want to consider surgical prevention options and could be a candidate for certain targeted cancer therapies."

What This Means For You

If you or a loved one has breast cancer, ask your healthcare provider about genetic testing. Research shows that genetic testing can help your provider recommend more precise treatment options. Genetic testing can also help you determine whether you (or your loved one) are at an increased risk for breast cancer and how to improve the prognosis. 

How Does Genetic Testing Work?

Nussbaum says that “Generally, genetic testing for a breast cancer patient is a simple blood test that a physician orders for a patient to determine if a patient’s cancer is related to an inherited condition or risk factor.”

The turnaround for the results of the test can vary. For example, a genetic test from Invitae usually takes 10 days to two weeks. However, the company also offers an expedited service that can provide results in seven to 10 days, if needed. 

Nussbaum says that the benefits of genetic testing also extend to the family members of a patient with breast cancer. “For her family, testing can identify other family members who may themselves be at increased risk for cancer and should be monitored more carefully," he says. 

Despite the benefits, studies (including the INTERCEPT study) have shown that the utilization of genetic testing in breast cancer patients remains low. For instance, a 2019 study published in the Journal of Clinical Oncology found that only 8% of breast cancer patients had been offered genetic testing.

What's the reason for the underutilization? “In the past, cost was a barrier but it’s one that has largely been addressed through both improving reimbursement and lower costs from testing providers," Nussbaum says. "I think what we’re seeing now is that restrictive, outdated testing guidelines exclude patients who could benefit from testing.” 

How Current Guidelines Hinder Genetic Testing 

“The guidelines of genetic testing are very complex and differ based on the type of cancer diagnosed,” Niloy Jewel (Jewel) J. Samadder, MD, director of the high-risk cancer clinic at the Mayo Clinic in Arizona, tells Verywell. “These criteria have been shown in our study and others to not be sensitive for ruling out the presence of a genetic cause of cancer.”

According to Samadder, guidelines have already been implemented to support genetic testing for patients with ovarian or pancreatic cancer. However, the same level of adoption has not been applied to other types of cancers, including breast cancer. 

“Based on the results of the INTERCEPT study (and other similar studies) the goal should be to offer genetic testing to any patient with a personal history of (any) cancer," Samadder says. "Mayo Clinic is taking the steps to make this a reality in 2021."

The clinic is working through steps to ensure that any patient who receives care at a Mayo Clinic Cancer Center will receive a comprehensive genomic evaluation designed to:

  • Identify the cause of their cancer
  • Determine the risk of cancer in their families 
  • Find precision-targeted therapies to improve their chance of survival

Despite the Mayo Clinic's groundbreaking move, it remains uncertain whether other healthcare organizations will follow suit.

The Future of Genetic Testing

“Genetic testing is certainly becoming more accepted but there is still a long way to go," Nussbaum says. “The problem is that guidelines are not updated as quickly as is our understanding of gene-disease relationships in this fast-moving field and they haven’t kept pace with the changes in cost and availability.”

In 2019, the American Society of Breast Surgeons (ASBS) released an official statement recommending that all breast cancer patients and their family members be offered genetic testing.

Nussbaum says that providers have been slow to follow the ASBS’ lead, but he is hopeful that "with the strong and growing evidence of the benefits of universal testing we’ll see guidelines begin to change and come to reflect what Mayo Clinic is making standard practice genetic testing for all cancer patients.”

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Article Sources
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  1. Invitae. JAMA Oncology Study Supports Germline Genetic Testing For All Cancer Patients. Updated October 30, 2020.

  2. Samadder NJ, Riegert-Johnson D, Boardman L, Rhodes D, Wick M, Okuno S, et al. Comparison of Universal Genetic Testing vs Guideline-Directed Targeted Testing for Patients With Hereditary Cancer Syndrome. JAMA Oncol. Published online October 30, 2020. doi:10.1001/jamaoncol.2020.6252

  3. National Cancer Institute. Fewer Women With Ovarian, Breast Cancer Undergo Genetic Testing Than Expected. Updated April 9, 2019.

  4. The American Society of Breast Surgeons. Official Statement: Consensus Guideline on Genetic Testing for Hereditary Breast Cancer. Updated February 10, 2019.