Racial Differences In Cancer Gene

Black women with breast cancer are four times more likely than white women with breast cancer to have mutations in a gene known to help suppress tumors, new research shows.

The mutations occur in a gene called p53. “P53 tumor mutations have for several years been known to be associated with a poor prognosis for breast cancer,” said study author Beth A. Jones, an assistant professor of epidemiology at the Yale University School of Medicine. The report appears in the Aug. 9 online issue of Cancer.

“But this is the first population-based study that shows a clearly significant race difference in p53 tumor mutations, once you adjust for other factors such as tumor stage,” Jones added.

Jones and her team evaluated the breast tumors of 145 black women and 177 white women, looking for differences in the p53 gene. Although they found black women were more likely to have p53 gene mutations, they didn’t find significant differences by race in any other cancer-related genes.

In the study, 24.5 percent of the black women had a p53 mutation, compared to 7.1 percent of the white women.

“Overall, the rates of breast cancer in African-American women are slightly lower than in white women,” Jones said, “but the death rate from breast cancer in African-American women is slightly higher than in white women.”

Discoveries of racial differences in genetic alterations such as the p53 gene mutation may explain why.

In an editorial accompanying the study, Dr. Lisa A. Newman, director of the Breast Care Center at the University of Michigan, notes the largest magnitude of difference in outcomes for breast cancer within the United States have been observed between black and white women. For those under the age of 45, the incidence of breast cancer is higher in black women than in white women, Newman wrote.

“Numerous studies, for at least 50 years, have been showing that African-American women are more likely to die from breast cancer than white American women, “ Newman said.

But researchers, she said, have never been able to sort out conclusively whether that is due to socioeconomic factors, poorer access to screening, diagnosis at an advanced stage or other factors. “Studies like this that look at some of the biological enhancers help us to figure out whether some women are more likely to develop inherently more aggressive tumors,” Newman said.

Dr. Denise Johnson, advising dean and associate professor of surgery at Stanford University Medical Center, and a member of the African-American Outreach Committee for the American Cancer Society, praised the study.

“It isn’t the first study on the topic, but it is the largest,” she said.

Eventually, Johnson said, the finding may provide more tools to determine the outlook for a woman with breast cancer, especially if she has the gene mutation.

Still, Johnson said more study was needed. If the finding holds up, she added, perhaps a recommendation will someday be made to analyze the presence or absence of the p53 gene mutation in all women.