African ancestry and aggressive disease

Reuters Health:

African American women, regardless of their socioeconomic status, have a significant and independent risk of having a worse breast cancer outcome compared with white women, according to a combined analysis of several clinical trials. This suggests that socioeconomic disparities alone do not explain the higher breast cancer mortality among African American women, and that other factors, such as genetics, tumor biology and cultural effects, need to be investigated.

Dr. Lisa A. Newman of the University of Michigan, Ann Arbor, and colleagues compared the survival rates according to ethnicity and socioeconomic status in 20 breast cancer studies.

As reported in the Journal of Clinical Oncology, a total of 14,013 African American women and 76,111 white women were involved in the studies, which were all reported between January 1980 and June 2005.

The term "ethnicity" was chosen over "race" because ethnicity "connotes some cultural commonality in addition to shared ancestry," the researchers explain. "Four centuries of intermarriage between Europeans, Africans, Scandinavians, and Asians who populate the United States 'melting pot' have resulted in substantial genetic (mixture) for most contemporary Americans," they add.

The only ethnic groups that most whites were intermarrying with were other white ethnic groups.

The researchers found that after accounting for the effects of patient age, tumor stage and socioeconomic status, there was an excess overall mortality risk among African American women, who were 27 percent more likely to die and 19 percent more likely to die of breast cancer.

The excess mortality risk among African American women was statistically significant, Newman and colleagues report.

The investigators also found that breast cancers among African Americans tended to occur at a younger age and were more advanced at the time of diagnosis than breast cancer whites. Breast cancers in African American women also tended to be more aggressive.

"The possibility of hereditary predisposition for aggressive disease related to African ancestry is currently being investigated," they write.

African-American women are more likely than white women to die of breast cancer