Rates of Invasive Breast Cancer Remain Stagnant Among Black Women After Decline in Use of Hormone Replacement Therapy, Study Finds
Rates of invasive breast cancer decreased significantly for white and Hispanic women between 2002 and 2004, but rates for black women essentially remained the same, according to a report presented on April 13 at an annual meeting of the American Association for Cancer Research, HealthDay/Washington Post reports. For the study, researchers led by Dezheng Huo, an epidemiologist at the University of Chicago Medical Center, examined data from 17 cancer registries covering about 26% of the U.S. population (Gordon, HealthDay/Washington Post, 4/15).
Researchers calculated breast cancer rates between 2000 and 2004 to determine whether trends were similar across racial and ethnic groups after a decline in use of hormone replacement therapy during the same period. Many women discontinued use of HRT after a study released in 2002 indicated that estrogen and progestin HRT might increase a woman's risk of cardiovascular disease and cancer, Reuters reports (Beasley, Reuters, 4/15). After HRT use dropped, rates of estrogen-receptor positive breast cancer declined sharply for white women ages 50 to 69 in the second half of 2002 and all of 2003, before stabilizing in 2004, Huo said. Estrogen-receptor positive tumors are those fed by estrogen, HealthDay/Post reports.
However, among black women, the rates remained the same during the time period, the study found. "In women in the age group from 50 to 69 -- those more likely to use hormone replacement therapy -- we found that the reduction in invasive breast cancer with estrogen-receptor positive tumors was [about] 13% for whites, 11% for Hispanics, about 4% for Asian or Pacific Islanders and no change for African-Americans," Huo said. Researchers also found a slight reduction in estrogen-receptor negative breast cancer for whites and Hispanics, as well as a slight increase for black women. About 80% of breast cancer tumors in white women are estrogen-receptor positive, compared with 60% in black women, according to the study.
Huo said black women's lower likelihood of having estrogen-receptor positive tumors could explain why they did not benefit from the decline in use of HRT. Another reason for the disparity could be that black women used HRT less frequently than whites to begin with, Huo added. An earlier baseline study found that prior to 2002, about 14% of white women used HRT, compared with 10% of black women, according to Elizabeth Ward, director of surveillance research for the American Cancer Society.
Huo said another possible reason for black women's rates is that mammography programs have not been effective in their communities. Ward said, "This is an area of a great deal of interest -- we've known that black women have a lower incidence of breast cancer, but higher mortality rates. No one really understands why" (HealthDay/Washington Post, 4/15).