The National Institutes of Health defines precision medicine as “An emerging approach for disease treatment and prevention that takes into account individual variability in genes, environment, and lifestyle for each person.” Without adequate representation of patient diversity, precision medicine based on data derived largely from Americans of northern European ancestry may actually exacerbate health disparities. Breast cancer is a highly prevalent, molecularly heterogeneous group of malignancies that remains a cause of significant morbidity and mortality worldwide. Much is known about the molecular landscape of breast cancers, their mutational and gene expression profiles. Molecular tests are widely used in the clinic to estimate breast cancer risk and its recurrence in patients treated for breast cancer. However, these tests are based on studies conducted in populations that at present include very small numbers of Latinas. As of December 2018, only 37 out of 3650 molecular profiles of breast cancer from The Cancer Genome Atlas are from women who reported Hispanic/Latina ethnicity, and no race or ethnicity information is associated with a majority of the cases (2735). Hence, the clinical usefulness of molecular breast cancer tests in Latinas of different ancestry admixtures remains to be established. Patients who are identified as Hispanic/Latino are characterized by highly variable ancestry admixtures, which makes genetic and gene–environment interaction studies particularly challenging. Our group has investigated the molecular portraits of breast cancers in a cohort of Colombian women and identified a high prevalence of luminal B subtype tumors characterized by high expression of proliferation-related genes and other clinically relevant genes. Furthermore, we have uncovered clinically relevant genes whose expression is significantly associated with Native American ancestry. Additional studies are needed to validate these findings in other Hispanic/Latina populations and to examine the gene sets included in popular molecular tests.
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