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Cancer Res. 2013 Dec 15;73(24):7243-53. doi: 10.1158/0008-5472.CAN-13-2014. Epub 2013 Oct 31.

Genetic ancestry and risk of mortality among U.S. Latinas with breast cancer.

Author information

1
Authors' Affiliations: Department of Medicine, Division of General Internal Medicine, Institute for Human Genetics, Helen Diller Family Comprehensive Cancer Center, Center for Aging in Diverse Communities, and Medical Effectiveness Research Center for Diverse Populations, University of California San Francisco, San Francisco; Cancer Prevention Institute of California, Fremont; Division of Epidemiology, Department of Health Research and Policy, and Stanford Cancer Institute, Stanford University School of Medicine, Stanford; and Department of Preventive Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine of University of Southern California, Los Angeles, California.

Abstract

Multiple studies have reported that Latina women in the United States are diagnosed with breast cancer at more advanced stages and have poorer survival than non-Latina White women. However, Latinas are a heterogeneous group with individuals having different proportions of European, Indigenous American, and African genetic ancestry. In this study, we evaluated the association between genetic ancestry and survival after breast cancer diagnosis among 899 Latina women from the San Francisco Bay area. Genetic ancestry was estimated from single-nucleotide polymorphisms from an Affymetrix 6.0 array and we used Cox proportional hazards models to evaluate the association between genetic ancestry and breast cancer-specific mortality (tests were two-sided). Women were followed for an average of 9 years during which 75 died from breast cancer. Our results showed that Individuals with higher Indigenous American ancestry had increased risk of breast cancer-specific mortality [HR: 1.57 per 25% increase in Indigenous American ancestry; 95% confidence interval (CI): 1.08-2.29]. Adjustment for demographic factors, tumor characteristics, and some treatment information did not explain the observed association (HR: 1.75; 95%CI, 1.12-2.74). In an analysis in which ancestry was dichotomized, the hazard of mortality showed a two-fold increase when comparing women with less than 50% Indigenous American ancestry to women with 50% or more [HR, 1.89, 95%CI, 1.10-3.24]. This was also reflected by Kaplan-Meier survival estimates (P for log-rank test of 0.003). Overall, results suggest that genetic factors and/or unmeasured differences in treatment or access to care should be further explored to understand and reduce ethnic disparities in breast cancer outcomes.

PMID:
24177181
PMCID:
PMC3881587
DOI:
10.1158/0008-5472.CAN-13-2014
[Indexed for MEDLINE]
Free PMC Article

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