Sunday, November 14, 2010 by: David Gutierrez, staff writer
NaturalNews Women of African ancestry are more likely to develop a more aggressive form of breast cancer known as “triple negative,” researchers have found, but the explanation for this correlation may have more to do with vitamin levels than with genetic predisposition.
Breast tumors may carry any combination of a variety of receptors, including estrogen receptors, progesterone receptors and HER-2/neu receptors. Because modern treatments have focused on targeting these three receptors, cancers that carry none of them — that are triple negative — are significantly harder to treat.
“Outcome disparities are therefore likely to increase, because fewer black women are candidates for these newer treatments,” said researcher Lisa A. Newman of the University of Michigan.
To conduct the study, which was published in the journal Cancer, researchers compared the types of breast cancer diagnosed in white and black women at the Henry Ford Health System in Detroit and African women at the Komfo Anokye Teaching Hospital in Ghana. They found that while only 16 percent of white and 26 percent of black participants had triple negative cancer, the rate was 82 percent among African women.
The researchers immediately proposed a genetic explanation for their findings, suggesting that African ancestry predisposes women to develop triple negative breast cancers. As evidence, they cited studies showing that while breast cancer rates are lower among black women in the United States than among white women, black women tend to develop cancers at a younger age, and those cancers are more aggressive and more likely to be fatal.
The data may be interpreted another way, however. For example, a number of studies have identified traits including obesity, excess weight gain since childhood, failure to breastfeed after pregnancy and use of lactation suppressants as risk factors for basal-type breast cancers, of which triple negative cancers are a subcategory.
Meanwhile, cancer researcher Sarah Gehlert of the University of Chicago is conducting research into the effect community factors on breast cancer risk.
“Women who live in areas with … a lot of violent crime, and who live in unsafe housing, without a lot of community support … will be more likely to have sporadic mutations and will have [worse outcomes] with breast cancer,” Gehlert said.
If women in Ghana and black women in Michigan live in more stressful, toxic environments than white Michigan women, this could partially explain the study’s findings. Notably, Ghanian women in the study were also likely to develop cancer younger and to have larger, more advanced tumors. Similarly, a higher rate of triple negative cancer has also been found among Hispanic women in the United States, whose genetic ancestry is quite different than African American women.
“We produce vitamin D from UV sunlight, but melanin — which gives dark skin its color — blocks UV light,” said Dr Helen Cooper of Birmingham University.
Vitamin D helps to regulate the immune system and has been associated with a lower risk of certain cancers. Researchers believe this is why rates of cancer are so much lower closer to the equator, where the sun is strongest.