Now, scientists at the University of North Carolina at Chapel Hill School of Medicine believe they have found another reason. A study they conducted shows doctors do a better job of advising whites to undergo mammography than advising blacks to have the life-saving test.
"Using North Carolina data, we found that in comparison with white women, black women were half as likely to report ever having had a mammogram -- 27 percent vs. 52 percent -- and having had a mammogram in the past year -- 17 percent vs. 36 percent," said Dr. Michael S. O?Malley, assistant director of the UNC Lineberger Comprehensive Cancer Center. "Black women also significantly less often reported that doctors recommended that they have mammography -- 25 percent vs. 52 percent."
A report on the findings appears in the May issue of the American Journal of Public Health which appears June 14. Co-authors of the report, both at UNC-CH, are Drs. Jo Anne L. Earp, chair of health behavior and health education at the School of Public Health, and Russell P. Harris, assistant professor of medicine.
"We found that while many factors were involved, including personal finances and attitudes about cancer, a doctor?'s recommendation was the single strongest predictor of whether a woman went on the have the test," O'Malley said. "In fact, once a doctor advised a woman to undergo mammography, race did not make a meaningful difference. Almost equal percentages of blacks and whites went on to have it."
For the new study, the researchers analyzed data from detailed telephone surveys Harris directed in the late 1980s about breast cancer, mammography use and other subjects in two eastern N.C. counties, New Hanover and Pitt. The data analyzed came from 948 women aged 50 and older.
"Substantial differences between blacks and whites showed up in education, income, attitudes about cancer and mammography, access to health care and other factors, but while controlling for those factors narrowed the racial gap in screening, it did not eliminate it," O'Malley said. "Controlling for physician recommendation virtually eliminated the gap by itself, accounting for 60 to 75 percent of the racial difference in mammography use."
The scientist said he and his colleagues had no reason to believe racism affected doctors' recommendations.
"While we don't yet know the reason for racial differences in advising, we think doctors are less likely to recommend the test for women who might not be able to afford it or who might not get the test even when a doctor recommends it," he said.
Data from more recent surveys indicates the black-white mammography rate gap has narrowed in some parts of the United States, O'Malley said. Still, he said, the gap likely remains in rural and medically under-served communities.
Through the state's health departments, North Carolina is fortunate to have county-level breast and cervical cancer control programs funded by the U.S. Centers for Disease Control and Prevention that provides mammography and PAP smears to women who cannot afford them, O'Malley said.
"This is part of a team effort, which includes the N.C. Breast Cancer Screening Program, that is designed to eliminate some of the social and economic barriers to controlling cancer," he said. "As someone once said, increasing mammography use is not a one-horse race -- you have to work on all kinds of barriers simultaneously. Nevertheless, understanding and defining the physician's role is crucial step in creasing breast cancer screening for all women."
Earp leads the N.C. Breast Cancer Screening Program, and the researchers now are analyzing new data that should show which women are encouraged to have the breast cancer test and why some are not.
The National Cancer Institute and the UNC Specialized Program of Research Excellence in Breast Cancer supported the UNC-CH research.
Note: O'Malley can be reached at (919) 966-3036 (w) or 932-5456.
Contact: David Williamson