Breast Cancer In Latinas: Are Hispanic Women At Greater Risk Due To Obesity?

According to the American Cancer Society, breast cancer will claim 40,000 lives this year. In the Hispanic/Latino community, breast cancer rates are relatively lower than those found in the Caucasian community, as data from the Fred Hutchinson Cancer Research Center cites that Latinas are one-third less likely to have breast cancer than non-Hispanic white women.

Now, a new study has found a correlation between obesity and increased risk of certain types of breast cancer in post-menopausal Hispanic women. One study — published Oct. 30 in the journal Cancer Epidemiology, Biomarkers & Prevention — found that overweight or obese Hispanic women are at greater risk for estrogen receptor-negative and progesterone receptor-positive breast tumors.

"We've known this for a long time for white women, but now we are seeing this also in Hispanic women," study author Esther John, a senior research scientist at the Cancer Prevention Institute of California, said in an American Institute for Cancer Research news release. "Breast cancer appears to have different risk factors in younger versus older women but by far, breast cancer is more common among postmenopausal women."

"This has huge implications for not just Hispanics but all women. We cannot change genetics or family history, but we can do something about obesity," she said. "You can eat less, choose healthier foods and do more physical activity. It may not be that easy but it's possible. And it's important for not just lowering breast cancer risk but for many other diseases."

In a recent international study, led by UC San Francisco researchers, has found a reason for the low rates of breast cancer in Latinas: most Hispanic women have a genetic variant, which is believed to have originated from indigenous Americans, that protects them.

"After our earliest studies we thought there might be a genetic variant that led to increased risk in European populations," said Elad Ziv, MD, professor of medicine and senior author of the study. "But what this latest work shows is that instead there is a protective variant in Native American and Latina populations."

The variant is one difference in the three billion "letters" in the human genome, also called a single-nucleotide polymorphism (SNP). According to the study — published in the October 20, 2014 issue of Nature Communications — this one variation (located on Chromosome 6, near a gene coding for an estrogen receptor known as ESR1) drastically reduces the risk of breast cancer. More specifically, the study found that women with the genetic variant have breast tissue that is less dense on mammograms. This is significant because "mammographic density" is correlated with breast cancer — high dense breast tissue on mammograms is a risk factor.

"We have detected something that is definitely relevant to the health of Latinas, who represent a large percentage of the population in California, and of other states such as Texas," said first author Laura Fejerman, PhD, assistant professor of medicine and a member of UCSF's Institute of Human Genetics. "This work was done as a collaboration of multiple investigators, many of us originally from Latin America. As a Latina myself, I am gratified that there are representatives of that population directly involved in research that concerns them."