Studies Show Genetics Contribute to Higher African American Mortality Rates
Studies Show Genetics Contribute to Higher African American Mortality Rates
March 22, 2005 - Evidence is growing that supports the contribution of factors such as genetics and biology to the higher breast cancer mortality rates in African American women. Currently, Caucasian women over 40 have the highest incidence rate for breast cancer in this country, but African American women at every age have a greater likelihood of dying from breast cancer. Incidence and death rates for other minorities are generally lower than those for Caucasian and African American women.
The study
Dr. Rowan Chlebowski, Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, is the lead investigator in a study published in the Journal of the National Cancer Institute on March 16, 2005. The study followed almost 260,000 postmenopausal women from the Women's Health Initiative for a median time of over six years. Specifically, it evaluated differences in incidence and mortality observed between African American women when compared to other minorities and to Caucasian women.
In the study, adjustments were made for risk factors. Women of similar socioeconomic backgrounds and women treated in the same health care systems and clinical trial groups were also compared.
The conclusions
The conclusions from the study were that risk factors could explain most differences seen in the different racial groups, but that this did not explain the differences seen in African Americans. Their breast cancers were more likely to be a higher grade and estrogen receptor-negative, which result in a poorer prognosis.
Additional studies
Other studies have offered additional research on a possible genetic mechanism. A homeobox gene, BP1, has been identified that is seen more often in African American women's breast tumors than in Caucasian women's tumors. This gene is associated with estrogen receptor-negative tumors and aggressive tumors. Another gene, p53, (mutations in p53 lead to loss of the ability to stop cells from multiplying, leading to tumor growth) has also been linked in research to the more aggressive tumors in African American women.
Another study released last week in Cancer, Early View, also suggests the existence of factors other than risk. Women in sub-Saharan Africa were evaluated by looking at data from 1988 to 2004. These women had a younger age at diagnosis, more advanced disease and higher death rates from breast cancer.
Potential impact of the studies
Recognizing and acknowledging that there may be differences within the African American population that could offer explanations for the increased mortality is a major first step in addressing this problem. Answering this question could go far in reducing the unequal outcomes that African Americans with breast cancer now face. A larger piece of the puzzle remains the area of disparity for minorities in general.
The Susan G. Komen Breast Cancer Foundation
The Susan G. Komen Breast Cancer Foundation will continue to identify and seek solutions to these disparities and fund research grants to answer the scientific questions. The Foundation continues to stress the need for early detection, regular screening and familiarity with family history and personal risk.
Listen to an interview about these studies (Source: NPR)
Sources:
Breast Cancer Facts & Figures 2003-2004, American Cancer Society
Rowan T. Chlebowski, et al, Ethnicity and Breast Cancer: Factors Influencing Differences in Incidence and Outcome, Journal of the National Cancer Institute, Vol. 97, No. 6; March 16, 2005, pp 439-448.
Alero Fregene, M.D., et al, Breast cancer in sub-Saharan Africa: How does it relate to breast cancer in African-American women?, Cancer, Early View, March 2005.
