Genetic variant may account for lower risk of breast cancer among Latinas

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A genetic variant helps explain why Latinas are at lower risk of breast cancer, according to recent research by a team from the University of California, San Francisco (UCSF).

The breast tissue of women who carry the variant appears less dense on mammograms, a factor known to help shield breast cancer.

Although it's been known that Latina women are less susceptible to breast cancer (Hispanics have less than a 10 percent lifetime risk, compared to 13 percent for whites and 11 percent for blacks, according to National Cancer Institute data from 2007-2009), the lowered risk has been attributed to lifestyle differences. The UCSF researchers suspected there may be more to it, and started examining DNA from 3,140 women with breast cancer and 8,184 healthy women.

They found that about 1 in 5 Latinas in the U.S. carry a protective variant — or single nucleotide polymorphism (SNP) — on Chromosome 6, The New York Times reports. According to the Times, the protective variant is associated with "indigenous ancestry" and occurs "with about 15 percent frequency in Mexico, 10 percent in Colombia and 5 percent in Puerto Rico. But its frequency [is] below 1 percent in whites and blacks."

"The variant is one difference in the three billion 'letters' in the human genome," the Latin Times reports, and "drastically reduces the risk of breast cancer."

Experts not involved in the study say the finding is important for several reasons.

“If we can understand how this is protective, it might help us to develop better treatments for those who do get breast cancer," Marc Hurlbert, executive director of the Avon Foundation Breast Cancer Crusade, told The New York Times.

Future research could determine whether the variant could "work as a protector for other groups,” Ysabel Duron, a cancer survivor who founded Latinas Contra Cancer, a group in San Jose that helps Latinos with issues related to all cancers, told SFGate. "And most importantly, there’s research happening on Latinas.”

Latinos account for 1 percent of clinical trial participants, even though they represent 16 percent of the U.S. population, according to the U.S. Food and Drug Administration, SFGate noted. They also get mammograms at a slightly lower rate, according to data from the Centers for Disease Control and Prevention:

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While the variant is associated with a lowered risk of breast cancer, it's not a panacea.

“I’m confident that this finding is going to hold, that most women who have this genetic variant are at lower risk of breast cancer,” Dr. Otis W. Brawley, the chief medical officer at the American Cancer Society, told The New York Times. “But keep in mind that some women with this variant still get breast cancer. It might be because they have this variant and something else that cancels it out.”

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