European ancestry increases breast cancer risk among Latinas

December 1, 2008

Latina women have a lower risk of breast cancer than European or African-American women generally, but those with higher European ancestry could be at increased risk, according to data published in the December 1 issue of Cancer Research, a journal of the American Association for Cancer Research.

"We need to study the possible factors that are placing Latina women of high European ancestry at greater risk," said Laura Fejerman, Ph.D., a post-doctoral research fellow at the University of California San Francisco. "The increased risk could be due to environmental factors, genetic factors or the interplay of the two."

Latinas are what geneticists refer to as an "admixed" population with most of their genetic ancestry from European or indigenous Americans. Fejerman said the term "indigenous Americans" usually refers to the groups that lived on the American continent prior to the arrival of the European colonizers.

For the current study, Fejerman and colleagues identified the genetic ancestry of 440 Latina women with breast cancer and 597 Latina women who did not have breast cancer.
For every 25 percent increase in European ancestry there is a 79 percent increase in the risk of breast cancer. If a woman had an estimated European ancestry of 25 percent she would be 79 percent more likely to have breast cancer than a woman of full indigenous American ancestry.

After accounting for known risk factors like number of full-term pregnancies or months of breastfeeding, the breast cancer risk for every 25 percent increase in European ancestry decreased to 39 percent, but it remained statistically significant.

Fejerman said that the overall risk of Latinas in the US is less than in European Americans but higher than indigenous Americans. She said further research would need to be conducted to determine if these differences are due to the presence of non-genetic risk factors that have not yet been described and that vary with ancestry, to the effect of genetic variants that either are protective or increase risk, or the result of the interaction between genes and non-genetic factors.

Source: American Association for Cancer Research

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not rated yet Dec 02, 2008
Dr. Fejerman,

I read this news report regarding your research into breast cancer among Latinas and felt compelled to question some of the basic assumptions forming your research.

The underlying premise of your study is that Latinas are a genetically distinct, though admittedly "admixed," racial group distinct from black or white women. However, I would argue this assumption is faulty for a number of reasons.

Your study explores at length the percentage of European and indigenous genetic ancestry among Latinas. Nowhere in the article I read about your study did I find an attempt to define the term Latina. What in medical terms constitutes a "Latina?"

Were these women selected on the basis of their last names? Were they chosen by their country of origin? Either choice poses questionable medical assumptions. In essence, you are concluding that every person with a Spanish surname or who originated in a Spanish-speaking country is part of distinct genetic category. Would you make that same assumption if a person had an Anglo name and came from an English-speaking country? By the logic you have apparently used to define Latinas, a white Englishwoman, a black Jamaican and an Australian aborigine would be part of a single "Britannic" genetic group.

There is a second significant flaw in your study: It limits the definition of Latina to someone of "admixed" European and indigenous ancestry.

This blanket assumption of all Latinas as mongrels is not only offensive, it is also inaccurate. In Uruguay and Argentina, for example, the percentage of the population of European descent is greater than in the United States. What's more, if you were to test the DNA of the U.S. population with Anglo surnames, you would likely find a significant presence of indigenous ancestry as well.

The definition of a Latina as someone of admixed European and indigenous ancestry suffers yet another flaw: This assumption totally ignores the presence of Latinas of African descent who make up roughly 18 percent of Latin America's population. (In contrast, African-Americans make up 12 percent of the U.S. population.) If the women you selected for your study were a true representative sample of "Latinas" surely some of them would have shown some indication of African ancestry in their DNA.

Dr. Fejerman, I realize you did not invent the term Latina or Hispanic and are doing your best to extend medical care to a segment of the U.S. population which studies have shown do not receive the same quality of medical treatment as mainstream Americans. I do not question your motives or your good intentions. But in trying to help a disadvantaged group, you are also perpetuating many of the misconceptions that feed fundamental prejudices.

The people of Latin America are not a single race. Studies like yours, while well intended, help foster this illusion.

I hope you will offer an explanation of these questions, not just to me, but to the journalists who have carried the story of your study to the public and the scientific community.

Raul Ramos y Sanchez
1 / 5 (1) Dec 02, 2008
Selected groups come from "Warmer Climates" and may have developed resistance or compliance!
not rated yet Dec 03, 2008
The article itself, published in Cancer Research in the December issue is very clear about its assumptions and none of the assumptions that Raul Ramos y Sanchez states in his comments are actually made in the study. Sometimes news based on scientific articles can be misleading since it is not possible to write a short news piece with the same level of detail that the scientific article has. My recomendation would be to read the article in Cancer Research to see what are the true assumptions of the study and what the conclusions mean. I think that this sould be the approach that everyone should have whenever they read news on a study that calls their attention for whatever reason.


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