Genetic Testing for Ancestral Origins May Propel Cancer Research to New Heights

Germline testing and genetic identification of a patient’s geographically defined ancestral background may improve researchers’ ability to discover more robust associations between race and cancer risk than relying on self-reported race and ethnicity alone, according to an article published in JAMA Surgery.¹

The impacts of race and ethnicity on cancer risk, progression, and outcomes have been widely reported, particularly the high cancer-related mortality rates commonly observed among African Americans. Despite the genetic admixture in the United States, many individuals self-identify as a single race or ethnicity. Using these self-reported data, cancer researchers studying the genetic and molecular factors associated with disease may not obtain the most optimal insight into the genetic associations between race, ethnicity, and cancer.

In this article, Lisa A. Newman, MD, MPH, and John Carpten, PhD, discuss the growing trend of consumer-based germline testing services and the potential advantage of using such tools for cancer research. Specifically, they argue that proteomic, genomic, and similar technologic advancements may help characterize the genetic components of ethnicity and race better than ambiguous self-reported racial and ethnic identity data, ultimately fueling future cancer research and assisting in the development of targeted therapies that have greater precision.

One example relating to the importance of genetic testing for cancer research is in African Americans. Although many individuals who self-report as African American have African ancestry, it is not uncommon for these individuals to have other ancestral origins resulting from centuries’ worth of genetic admixture. For example, western sub-Saharan African women have a higher risk for estrogen-receptor-negative breast cancer and triple-negative breast cancer, whereas East African women share a similar genetic risk profile to that of white American and European women.^2-4 These findings demonstrate the need for a higher level of genetic testing in research studies focused on cancer, which may help reduce broad generalizations across racial and ethnic groups in America.

The public has increasingly demanded genetic testing services to determine specific geographically defined ancestry. Drs Newman and Carpten suggest that “genotyping is simply one more device in the molecular and genetic epidemiology toolbox; we should follow the lead of the general public and use this tool to understand and conquer the cancer burden of our diverse patient population.”

References

1. Newman LA, Carpten J. Integrating the genetics of race and ethnicity into cancer research: trailing Jane and John Q. Public [published online January 24, 2018]. JAMA Surg. doi:10.1001/jamasurg.2017.5080.
2. Jemal A, Fedewa SA. Is the prevalence of ER-negative breast cancer in the US higher among Africa-born than US-born black women? Breast Cancer Res Treat. 2012;135(3):867-873.
3. Newman LA, Kaljee LM. Health disparities and triple-negative breast cancer in African American women: a review. JAMA Surg. 2017;152(5):485-493.
4. Huo D, Feng Y, Haddad S, et al. Genome-wide association studies in women of African ancestry identified 3q26.21 as a novel susceptibility locus for oestrogen receptor negative breast cancer. Hum Mol Genet. 2016;25(21):4835-4846.