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One of the largest studies of young Black women with invasive breast cancer has identified a high prevalence of specific hereditary breast cancer (HBC) genetic variants, underscoring the importance of genetic testing in this group.

Out of 686 participants who underwent germline genetic testing,15.3% carried a pathogenic or likely pathogenic variant, mostly in the BRCA1 or BRCA2 genes. The new research also found that Black women face similar hereditary cancer risks as White women.

“Our study demonstrates that Black women are at risk of inherited breast cancer, similar to other populations, yet get testing at lower rates,” lead author Tuya Pal, MD, told Medscape Medical News. “The age distribution and type of breast cancer based on receptor status by gene are similar to that reported in White women.”

Most of the women with higher-risk genetic mutations for breast cancer had a family history. Although many patients without a family history also had inherited cancer, added Pal, who is a professor of genetic medicine and a cancer researcher at Vanderbilt University Medical Center in Nashville, Tennessee.

What Was the Rationale for the Study?

Young Black women have been underrepresented in genetics research. Overall, Black women have a lower incidence of breast cancer, but young Black women have higher rates of breast cancer, Pal explained.

“We thought that genetic predisposition might account for some of this.”

One of the risk factors for inherited cancer susceptibility is an early age or onset, she continued.

Pal said she and her colleagues sought to answer: “What is the impact of hereditary cancers on young black women?”

“We haven’t studied [these women] at the same level as other women,” she noted.

How Was the Study Done, and What Did It Find?

The study, published online in the journal Cancer, recruited 785 Black women who had been diagnosed with invasive breast cancer at an average age of 42.3 years from 2005 to 2018 through state cancer registries in Florida and Tennessee. More than 25% of the participants had triple-negative breast cancer. The vast majority (96.4%) had nonmetastatic disease, 81.5% had invasive ductal carcinoma, and 57.6% had high-grade tumors. The study authors claimed it is among the largest to characterize HBC in comparison to sporadic breast cancers using a registry-based sample of Black women diagnosed with breast cancer at age 50 years or younger.

Of the germline pathogenic or likely pathogenic variants detected, 50% of the women had BRCA1 (n = 53) and 29.5% had BRCA2 (n = 32). The study also found that most participants with germline pathogenic or likely pathogenic variants were of West African ancestry, confirming previously reported research by Pal and her group using the same registries. West African ancestry was linked to 72% of those with BRCA1 variants and 73% of those with BRCA2 variants.

“[This] tells us that inherited cancer predisposition is just as important in Black women as it is in White women,” Pal said. “If anything, some of the mutation frequencies that we saw may even be higher.” 

What Does the Study Add to Past Literature?

The study contributes more evidence of the role of HBC in Black women, Pal said.

“If women don’t get tested, they can’t benefit from the downstream benefits that can come from testing, such as personalized treatments, screening for other cancers for which they are also at high risk and sharing this information with family members so they too can get testing.”

Black women younger than 50 years would be eligible for germline testing under the current National Comprehensive Cancer Network guidelines, updated this year, Pal noted.

What Was the Most Surprising Finding?

The high rate of mutation frequency — 15.3% with germline pathogenic or likely pathogenic variants detected on genetic testing — was “quite high,” Pal said. “This has also been seen in some other studies, but it tells us that HBC testing is just as important in Black women as it is in other populations, and possibly even more important.”

What Are the Potential Practice-Changing Implications?

The study is a call to action for more aggressive germline testing for breast cancer variants in Black women, Pal said.

She also explained additional steps that need to be taken after testing.

“Testing itself is not going to improve outcomes,” she said. “It’s what you do about it that’s going to improve outcomes. So once you test, we need to make sure that these patients are getting the correct information and sometimes genetic counseling.”

If testing identifies people at risk, “we need to make sure that we’re providing them with care or else it’s not going to help them,” Pal added. In patients with a confirmed diagnosis of breast cancer, genetic testing can guide targeted therapies and also calculate future cancer risks.

When patients receive genetic testing, it creates “a tremendous opportunity to spread this information so their relatives can benefit as well,” she noted.

“Those things need to be discussed and disseminated across families or at least we need to help with doing that and inform our patients about that,” explained Pal.

The study results also expose a gap in Medicare coverage that breast cancer advocates are trying to address. Medicare does not provide coverage for additional breast cancer screenings or risk-reducing surgeries for women aged 65 years or older, a policy the hereditary cancer advocacy group FORCE is attempting to correct with legislation.

Commentary

The study findings add important population-based data on the role of hereditary risk and breast cancer in young Black women, said Allison W. Kurian, MD, MSc, director of the women’s clinical cancer genetics program at Stanford University in Palo Alto, California.

“The fact that they are population-based means that they are representative of the average young Black woman with breast cancer and thus a very useful reference point,” she said. “The key takeaway is that pathogenic variants in cancer risk genes are common in young Black women with breast cancer, clinical features of the cancers are similar to those in other groups, and appropriate genetic testing is crucial to enable optimal care.”

Kurian agreed with Pal’s assessment that Black women aged 50 years or younger with invasive breast cancer meet national guidelines for genetic testing. Her own group’s large population-based study found that Black women are substantially less likely than other women to get medically indicated genetic testing.

Pal and Kurian reported having no relevant financial relationships.

Richard Mark Kirkner is a medical journalist based in Philadelphia.