Cancer and Ethnicity

Results from a collaborative study show a significant difference between different ethnic groups and the likelihood of hereditary genetic mutations that are linked to breast cancer.

In a study from Mayo Clinic and Ambry Genetics of nearly 78,000 breast cancer patients, researchers identified important similarities and differences in hereditary predisposition to breast cancer across major racial/ethnic groups.

The similarities included:

• Pathogenic mutations [in 12 breast cancer predisposition genes] are prevalent across all major racial/ethnic groups, ranging from 7.5% in Asians and Ashkenazi Jews to 9.9% in Hispanics.

• Several genes, including BRCA1, BRCA2, and PALB2 are associated with a high risk of breast cancer across all major racial/ethnic groups.

The differences included:

• BRCA1 mutations were enriched in Blacks, Hispanics, Asians, and Ashkenazi Jews compared to non-Hispanic Whites and BRCA2 mutations were enriched in Blacks and Hispanics compared to non-Hispanic Whites.

• Variants of Uncertain Significance were higher in Blacks, Hispanics, and Asians compared to Non-Hispanic Whites and patients of Ashkenazi Jewish ancestry.

• For some genes such as RAD51C, the associated breast cancer risk varies between racial/ethnic groups.

“Based on the findings, healthcare executives should be aware that Ambry Genetics’ hereditary cancer multigene panel tests identify clinically actionable mutations in breast cancer patients across all major racial/ethnic groups,” says Holly LaDuca, Ms, CGC, senior manager, clinical affairs research at Amber Genetics. “In addition, we identified some gene- and population-specific breast cancer risk information that is relevant for patients of ethnic minorities, which have historically been underrepresented in studies of genetic risk for breast cancer.”

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 It is critical that healthcare executives work with genetic testing laboratories to offer comprehensive testing options that accommodate all ethnic groups to optimize personalized clinical care, according to LaDuca.

“We analyzed the data in several ways,” says LaDuca. “First, we compared the prevalence of mutations in all racial/ethnic populations to non-Hispanic Whites to understand whether mutations in any genes were similar or different across populations. We then compared the frequency of mutations in each major racial/ethnic group to the respective reference controls from the Genome Aggregation Database to estimate gene-specific breast cancer risk in each population. We also performed a number of supplementary analyses to account for potential confounders and other factors to limit bias in our results and better understand some of the correlations identified in the primary analyses.”

Unique finding

Another unique finding is that Blacks, Hispanics, and Asians were diagnosed with breast cancer and underwent genetic testing at younger ages than Non-Hispanic Whites and Ashkenazi Jews. This piqued the investigators’ interest in further exploring potential reasons for these differences, such as biologic differences in breast cancer incidence by ethnic group vs. disparity in access to genetic testing or personal/cultural drivers to pursue genetic testing.

“Healthcare executives should identify opportunities to make cancer genetic counseling and testing accessible to patients of all races/ethnicities and ensure comprehensive testing is offered that encompasses risks for all ethnicities,” says LaDuca.