Experts are divided over the reasons why
By Kathleen Doheny
HealthDay Reporter
TUESDAY, July 10 (HealthDay News) -- Black women diagnosed with breast cancer have more advanced and more aggressive disease than do white women, a new study found.
"It has been known for a long time that black women have a lower incidence of breast cancer than do white women, [yet] the mortality rate is higher in African-American women," said study leader Dr. Gloria Morris, assistant professor of medicine at the Kimmel Cancer Center at Thomas Jefferson University Hospital, in Philadelphia.
Exactly why that is so has been under debate in medical circles, Morris said. "There have been many hypotheses," she said, including genetic components, dietary factors, less access to health care and screening, and other possibilities.
Morris and her colleagues compiled pathology data from two databases: the large National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) database, with almost 200,000 women diagnosed with breast cancer between 1990 and 2000, and the database from Thomas Jefferson University Hospital, which included 2,230 women diagnosed between 1995 and 2002.
The researchers compared demographic, clinical and molecular breast cancer data in the two databases. They found that in both databases, black women had more advanced disease at diagnosis and a poorer prognosis.
"We found that in our registry, across the board, African-Americans presented with higher staged tumors, higher grade of tumors as well as more estrogen-receptor negative tumors," Morris said. Estrogen-receptor negative tumors are typically more aggressive than estrogen-receptor positive ones.
While 48 percent of black women were estrogen-receptor negative, 37 percent of white women were. Black women also tended to have higher rates of expression of the so-called "poor prognostic" genes, ki-67 and p53. While 42 percent of black women had the poor prognostic genes, just 29 percent of white women did.
"It shows us there are indeed multifactorial differences which include biologic differences, which we want to highlight from this study," Morris said.
Morris said she hopes the study will result in "heightened awareness in African-American women and those at higher risk that early intervention is really the key to improving survival."
The findings are published in the Aug. 15 issue of the journal Cancer.
Dr. Len Lichtenfeld, deputy chief medical officer for the American Cancer Society, said the study results add valuable information to the debates over the reasons for the differences in breast cancer rates among racial and ethnic groups.
"Some experts are adamant, it's all socioeconomic; others that there are biologic differences," Lichtenfeld said.
The new study, he added, "really does demonstrate there are some disturbing biological differences."
"Stage for stage, the situation is more serious for African-American women and [this study] lends credence to the fact that we need to be aware there may be some underlying biologic differences to explain the poorer outcome," he said. "However, we must still absolutely emphasize the fact that many African-American women do not have equal access to health care and treatment. And we cannot use this data as an excuse to ignore that fact."
SOURCES: Gloria Morris, M.D., Ph.D., assistant professor of medicine, department of medical oncology, Kimmel Cancer Center, Thomas Jefferson University Hospital, Philadelphia; Len Lichtenfeld, M.D., chief deputy medical officer, American Cancer Society, Atlanta; July 9, 2007, online edition, and Aug. 15, 2007, print edition, Cancer
Copyright © 2006 ScoutNews, LLC. All rights reserved.
