How does race affect breast cancer risk?

By Trisha Henry
CNN Medical News Producer

It's been long known that Hispanic women are less likely to get breast cancer than white women but now a new study examines why.

Researchers at the University of Colorado at Colorado Springs studied women with breast cancer. Among the white women, between 62 percent and 75 percent had known risk factors for breast cancer – behaviors or traits that have been found to increase one’s chances of getting the disease, for example, use of hormone replacement therapy.

Among Hispanic women, between 7 percent and 36 percent had known risk factors. "The whole intent was to shed light on why there are these differences," said the study's author, Lisa Hines, a University of Colorado at Colorado Springs assistant professor.

Traits found in Hispanic women in the study that did increase their breast cancer risk included having their first period younger, not breastfeeding their children and having a low level of physical activity. But other factors that usually increase the risk – alcohol consumption and higher body mass – didn't appear to have as much effect.  In general, Hispanic women were found to have more traits that would keep them in the clear than those that put them at risk. Even in premenopausal women, being taller and having a family history of breast cancer increased the risk of getting breast cancer in non-Hispanic white women but was found not to among Hispanic women.

Hines found that when it came to hormone replacement therapy, "post-menopausal non-Hispanic white women who had used hormone replacement therapy recently had an increased risk of getting diagnosed with breast cancer," but in Hispanic women, "there was no relationship with recent hormone replacement use" and breast cancer. The study also suggests the difference in estrogen exposure could be because of genetic, environmental, or lifestyle factors that make someone more likely to develop post-menopausal breast cancer. While previous studies have found that Hispanic women have a lower rate of breast cancer than non-Hispanic white women, they experience a higher risk of mortality after diagnosis. The question remains, what makes these two groups so different? Hines says it will take more research to determine what is causing fewer Hispanic women to develop breast cancer and "if there is something biologically that is making Hispanic women less susceptible, maybe someone can develop a strategy that can kind of mimic that."

The study found overall, non-Hispanic white women had a higher incidence of breast cancer compared with Hispanic women for every age group examined. This is one of the largest studies that have both non-Hispanic white women and Hispanic women in it and it's the only one to review both groups simultaneously.

Editor's Note: Medical news is a popular but sensitive subject rooted in science. We receive many comments on this blog each day; not all are posted. Our hope is that much will be learned from the sharing of useful information and personal experiences based on the medical and health topics of the blog. We encourage you to focus your comments on those medical and health topics and we appreciate your input. Thank you for your participation.