Oncologists at the Kimmel Cancer Center at Jefferson have found that breast cancer is more aggressive in African-American women.

The research, led by Dr. Edith P. Mitchell, clinical professor of medicine and medical oncology at Jefferson Medical College of Thomas Jefferson University, and Dr. Gloria Morris, assistant professor of medical oncology at Jefferson Medical College, found that African-American women tend to have more advanced breast cancer at the time of diagnosis and have poorer outcomes.

Reporting their findings online, July 9 in the journal “Cancer,” the researchers say the study provides powerful evidence of the continuing need for early breast cancer screening for African-American women and the development of individual treatment strategies. The research is consistent with other studies that claim African-American women tend to have more aggressive tumor types.

“It’s very disturbing that even though we know that incidences of breast cancer in African-American women are lower than it is Caucasian women, the likelihood of mortality from breast cancer in higher in African-American women. So the death rate is higher,” Morris said.

“There’s been multiple attempts historically to try to explain why.”

Mitchell, Morris and their colleagues compared clinical, molecular and demographic data from 2,230 African-American and Caucasian women diagnosed with breast cancer at Thomas Jefferson University Hospital between 1995 and 2002 with similar data on over 197,000 women in the National Cancer Institute’s Surveillance, Epidemiology and End Results database.

When all stages of breast cancer in Jefferson’s patients were analyzed, the results showed that African-American women had tumors that were often estrogen-receptor negative (48 percent versus 27 percent), had higher rates of the growth-promoting gene Ki-67 and a higher expression of a tumor-inhibiting gene, p53. A more aggressive tumor referred to as “triple negative” was found in 21 percent of African-American women compared to 10 percent of Caucasians.

“All of this tells us that there are likely other growth signals independent of hormonal stimulation that are causing these breast cancers to be more aggressive in African Americans as compared with Caucasians. So we have a lot of preliminary data and a lot of thrust to move forward with very specific molecular studies to try to explain that difference at the gene level,” Morris said.

The triple negative status of a tumor renders commonly used breast cancer drugs ineffective, which means that doctors must rely on chemotherapy as a treatment option.

“We’re finding that despite chemotherapy, this triple negative, basal phenotype still can either recur or become drug-resistant, so we are trying to find ways by doing research at the molecular level to identify a target for new drugs and a target for new biologic therapy for these types of tumors,” Morris added.

These tumors lack estrogen and progesterone receptors, which results in the lack of effectiveness of the breast cancer drug tamoxifen. The tumors also lack the HER2-neu receptor protein, rendering the drug Herceptin ineffective.

“We would like to explore future research that will enhance our knowledge and allow better understanding of these biological differences and diverse better treatment plans that could potentially be more effective,” Mitchell said in a release.

Though access to health care is a strong factor contributing to disparities in cancer rates and outcomes between African Americans and Caucasians, says Mitchell, the Jefferson study and others have shown that biological differences play important roles.

While they are starting to see more women coming in to be screened for breast cancer, Morris says that there is still more work to do when it comes to building awareness.

“We still have a lot of work to do in the community to heighten awareness that this is a significant problem and that mammograms and monthly breast self-exams should really be highlighted as very, very important because they can certainly save lives. We need to have patients have more accessibility to health care and regular health screenings,” Mitchell said.