Genes may play role in breast cancer racial disparities

May 12, 2017|ObGyn

FROM JAMA ONCOLOGY

A new analysis of data from The Cancer Genome Atlas revealed 142 genes differentially expressed between white and African Americans that may influence breast cancer survival.

Researchers sifted through gene expression, protein expression, somatic mutations, somatic DNA copy number alteration, and DNA methylation patterns between 154 black patients of African ancestry (mean age at diagnosis, 55.66 years); and 776 white patients (mean age, 59.51) of European ancestry. They also looked at germline genetic variants for breast cancer subtypes and estimated subtype heritability.

African American patients were more likely than were whites to have basal-like breast cancer (odds ratio [OR], 3.80; 95% confidence interval [CI], 2.46-5.87; P less than .001) and HER2-enriched breast cancer (OR, 2.22; 95% CI, 1.10-4.47; P =.027).

After adjustment for subtype, 142 genes were differentially expressed between the two populations, a finding that held true after correction for testing of multiple comparisons (Bonferroni-adjusted P less than .05), reported Dezheng Huo, MD, PhD, of the department of public health sciences, University of Chicago, and his coauthors (JAMA Oncol. 2017 May 4. doi: 10.1001/jamaoncol.2017.0595).

During a median follow-up of 29 months, African Americans were more likely to experience recurrences (hazard ratio [HR], HR = 1.67, 95 CI, 1.02-2.74; P =.043). They had higher odds of basal-like breast cancer (OR, 3.80; 95% CI, 2.46-5.87; P less than .001) and human epidermal growth factor receptor 2 ERBB2 (HER2)-enriched breast cancer (OR, 2.22; 95% CI, 1.10-4.47; P =.027).

After adjusting for intrinsic subtypes, the researchers found differential expression of 16 DNA methylation probes, 4 DNA copy number segments, and 1 protein,

“It gives us a road map to begin to dig deeper into solving a lot of the challenges we had had in terms of describing disparities, and what we need to do to move forward,” coauthor Olufunmilayo I. Olopade, MD, professor of medicine and human genetics and director of the center for clinical cancer genetics at the University of Chicago, said in a press statement.

“If you have African ancestry, you’re more likely to have tumors that grow really fast. If we have drugs that can treat that kind of tumor, we need to find you and get you into treatment as quickly as possible,” she said.