Study Finds Racial Differences in Somatic Alterations Shared by Prostate and Breast Cancers

A study published in BMC Medical Genomics found racial differences in somatic copy number alterations (SCNAs) shared by breast cancer and prostate cancer (Pca).

Both breast cancer and PCa are known for racial differences in both incidence and outcomes. African American (AA) men are almost twice as likely to be diagnosed with PCa, compared with European American (EA) men, and 2.3 times more likely to die from the disease. Regarding breast cancer, while incidences are slightly higher in EA women, mortality rates for the disease are 40% higher in AA women. The mortality gap in breast cancer may be explained by molecular differences between these two racial groups, and while these differences have been investigated separately in both races, this study represents the first time the degree to which somatic alterations that differ by race has been analyzed.

Researchers used data from The Cancer Genome Atlas (TCGA) to identify SCNAs that differed by race in breast (n=58 SCNAs), and prostate tumors (n=78 SCNAs). In both cancers, differences in SCNA magnitude were assessed using linear regression. Hierarchical clustering and Cox proportional hazards regression were used to evaluate any links between the racial groups and overall and progression-free survival.

According to the results, six race differentiated SCNAs common to breast and prostate tumors found were identified in several chromosomes and exhibited consistent differences by race across both tumor types, and all six were of higher magnitude in AAs. “We demonstrated that a majority of race-differentiated SCNAs in breast and prostate tumors have greater magnitude alterations in AAs relative to EAs and that this was the case for all of six race-differentiated SCNAs that were shared consistently across these tumor types,” the researchers concluded. “Combined, these findings suggest that breast and prostate tumor genomes of AAs may be more susceptible to SCNAs that underlie a more aggressive phenotype. This information may be useful for deciding whether adjuvant treatment is needed after surgery in the subset of patients with SCNAs associated with worse outcomes.”