An increased proportion of indigenous American ancestry was associated with a greater incidence of HER2-positive breast cancer, according to a study published in Cancer Research.1
“The risk of breast cancer–related mortality varies between different populations, with Latina women having a greater risk of breast cancer–specific mortality than non-Hispanic white women,” said Laura Fejerman, PhD, Associate Professor of Medicine at the University of California, San Francisco. Dr. Fejerman is lead author of the study, and she commented on the findings in a news release issued by the American Association for Cancer Research.
“Latina women tend to be diagnosed with more aggressive breast cancer subtypes, which may contribute to their greater risk of mortality, among other factors,” Dr. Fejerman said.
Previous work from Dr. Fejerman and colleagues demonstrated that indigenous American ancestry was associated with a lower incidence of breast cancer. However, the influence of indigenous American ancestry on different breast cancer subtypes remained unclear. A prior study that examined a small cohort of Colombian patients with breast cancer suggested that a higher proportion of indigenous American ancestry was associated with increased expression of the ERBB2 gene. This led Dr. Fejerman and colleagues to examine whether indigenous American ancestry may be associated with risk of HER2-positive breast cancer.
Peruvian Genetics and Genomics of Breast Cancer Study
The Peruvian Genetics and Genomics of Breast Cancer study (PEGEN-BC), led by Dr. Fejerman and developed in collaboration with Tatiana Vidaurre, MD, PhD, of the Instituto de Enfermedades Neoplásicas (INEN) in Lima, Peru, recruited 1,842 patients. Participants at INEN were invited to participate in the study if they had received a diagnosis of invasive breast cancer during or after the year 2010 and were between the ages of 21 and 79 years.
The publication reported results from 1,312 patients who had available genome-wide genotype data. HER2-positive breast cancers accounted for 30% of cases (18% were positive for hormone receptors). On average, participants had approximately 76% indigenous American ancestry, with 9.8% of patients having greater than 95% indigenous American ancestry.
Analyses revealed statistically significant differences in the distribution of different breast cancer subtypes among women with different proportions of indigenous American ancestry. The odds of having a HER2-positive tumor were 1.19 times higher for every 10% increase in indigenous American ancestry. Conversely, the odds of developing HER2-positive disease decreased with increasing European ancestry. The odds of having a HER2-positive tumor in these cohorts were approximately 1.28 times greater for every 10% increase in indigenous American ancestry.
Disclosure: Drs. Fejerman and Vidaurre reported no conflicts of interest. The PEGEN-BC study was supported by the National Institutes of Health/National Cancer Institute and the Instituto Nacional de Enfermedades Neoplásicas.