New research links risk of breast cancer to ethnicity

Not all breast cancers are created equal.

New genetics research by Olufunmilayo Olopade, a professor in the Department of Medicine and Human Genetics at the University of Chicago, suggests that the type and severity of breast cancer are largely dependent on patients’ ethnicity. Olopade determined that genes belonging to African-American women often have mutations similar to those found in African women in Nigeria. These same ethnically linked mutations may be the reason that African-American women are at a higher risk for more aggressive breast cancer, suggesting a relationship between mutations and different ethnic groups which has important implications for new, more effective methods of cancer treatment.

Olopade presented her findings to a group of about 30 medical professionals at the Yale Cancer Center Tuesday morning. The key to understanding the genetics of cancer lies in studying families or large groups of ethnically homogeneous people, she said.

Olopade is the founding director of the Center for Clinical Cancer Genetics at the University of Chicago, and has conducted field research in Iceland and in her home country of Nigeria, both of which contain concentrated groups of ethnically similar women. In both groups, Olopade found that various cancer genes were similar among women of the same ethnic background.

“Breast cancer is not just one disease,” Olopade said. “It is different for everyone.”

Olopade found that African women are prone to tumors that are estrogen-receptor negative and therefore do not respond well to traditional treatments that are generally helpful to Caucasian women. Olopade also traced another mutation, in the BRCA1 gene, from women in West Africa to African-American women, concluding that the mutation was carried over on slave ships.

“This [mutation] may be why African-American women are more likely to get aggressive breast cancer, but less likely to get cancer in general,” Olopade said.

Attendees at yesterday’s presentation said they think Olopade’s findings indicate a need for more extensive investigation into the mutations and their relationship to race so that proper treatments can be devised for specific ethnic groups.

Onyi Offor MED ’10, whom Olopade has mentored, said she thinks the importance of Olopade’s study lies in its focus on the role of race in cancer treatment.

“One size doesn’t fit all,” Offor said. “And clearly racial differences need to factor in to treatment decisions. We also need to do more studies.”

But Maysa Abu-Khalaf, an oncology professor at the Yale Cancer Center, said the study proves doctors cannot simply group patients together by race. What is important to creating more effective cancer treatment methods is the type of mutation, and that will require better detection and more research, she said.

Olopade echoed these sentiments in her presentation.

“What was previously an issue of black and white is now proving to have shades of gray,” Olopade said. “There are no definite answers.”

Olopade is a graduate of the University of Ibadan in Nigeria and a Walter L. Palmer Distinguished Service Professor at the University of Chicago.

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