Researchers have long known that Latina women have lower rates of breast cancer compared to African-American and white women. They have mainly pointed to lifestyle and environmental factors to explain why –- Latinas tend to have more children, breast feed longer, and drink less alcohol, all factors that are associated with lower disease rates.
Now, an international study led by scientists at UC San Francisco shows that a genetic variant unique to Latina women with indigenous ancestry plays a significant role, too.
“When we were accounting for all the non-genetic risk factors in our analysis, it was not enough to explain that women with more indigenous American ancestry tended to have less breast cancer,” says lead author Prof. Laura Fejerman, a member of UCSF's Institute of Human Genetics.
About one in five U.S. Latinas have the variant. Women with one copy of the variant are 40 percent less likely to develop the disease, while women with two copies have an 80 percent reduction in risk.