Sue A. Joslyn, PhD, lead study author and Associate Professor of Epidemiology at the University of Northern Iowa, and her colleague, Michele M. West, PhD, of the State Health Registry of Iowa and the University of Iowa, analyzed data for 135,424 women diagnosed with primary breast cancer between 1988 and 1995. The data were acquired from the National Cancer Institute's Surveillance, Epidemiology, and End Results Program.

The researchers concluded there is need for further research into the causes of racial differences. They also suggested there is a need for public health measures designed to increase breast cancer education and screening among African-American women.

The researchers suggested several key reasons for the disparity they found between African-American and white women with breast cancer. Cultural and socioeconomic factors might mean African Americans have less access to screening, early detection, and treatment of breast cancer, according to the researchers. In the US, where racial minorities have a lower socioeconomic status, variables such as low income, lack of private health insurance, lack of transportation, and lack of access to health care may be barriers to diagnosis and treatment.

The authors also pointed out that African-American women are not as likely as white women to seek mammograms and are more likely to delay reporting signs and symptoms of breast cancer to their doctors. They are more likely to miss health care appointments after diagnosis and experience more obesity, which has been linked to diagnosis at a later stage and poorer outcomes.

Fear of radiation also was found to be a barrier to mammography for some African-American women. One study cited by the authors revealed cultural beliefs that prevent African-American women from seeking cancer screening.

Although barriers to diagnosis and treatment help explain some of the researchers' observations, such as more advanced spread at the time of diagnosis, they do not explain others, such as younger age at diagnosis found in African-American women or subtle biological differences in the cancers.

In addition to the socioeconomic and cultural factors, there also appears to be pathological differences in tumor characteristics between races. African-American women are more likely to be diagnosed with estrogen and progesterone receptor-negative tumors, which contribute to a poorer prognosis when compared with hormone receptor-positive tumors.

Suggesting this would be an area for researchers to explore further, Dr. Joslyn noted that these estrogen and progesterone receptor-negative tumors tend to be more aggressive and more difficult to treat than hormone receptor-positive tumors. Other forms of breast cancer associated with poor prognosis, such as inflammatory carcinoma, are also more common among African Americans.

The difference in the tumors underscores the need for early detection, according to Dr. Joslyn and Hugh F. Stallworth, MD, MPH, National Vice President of Cancer Risks at the American Cancer Society (ACS). Another argument for early detection, Dr. Stallworth said, is that African-American women don’t get breast cancer at a higher rate than white women, but that they die from it at a higher rate.

Breast cancer is the most common cancer among women and the second most deadly. It remains the leading cancer killer among African-American women.