Breast cancer survival is, over all, three years shorter for black women compared with white women, mostly because their cancer is often more advanced when they first seek medical care, new research shows.
While cancer researchers have known for two decades that black women with breast cancer tend to fare worse than white women, questions remain about the reasons behind the black-white divide. The new report, from researchers at the University of Pennsylvania, begins to untangle some of the issues by using an analytic method to filter the influence of demographics, treatment differences and variations in tumor characteristics, among other things.
The findings, published in The Journal of the American Medical Association, suggest that while a significant number of black women still get inferior cancer care, the larger problem appears to be that black women get less health care over all, and that screening and early detection campaigns may have failed to reach black communities.
Using data from Medicare patients tracked in the Surveillance, Epidemiology and End Results database, the researchers analyzed 107,273 breast cancer cases, which included 7,375 black women. The larger number of cases involving white women allowed researchers to find nearly perfectly matched controls against which to compare the outcomes of black women with breast cancer.
The findings were striking. Over all, white women with breast cancer lived three years longer than black women. Of the women studied, nearly 70 percent of white women lived at least five years after diagnosis, while 56 percent of black women were still alive five years later.
The difference is not explained by more aggressive cancers among black women. Instead, the researchers found a troubling pattern in which black women were less likely to receive a diagnosis when their cancer was at an early stage and most curable. In addition, a significant number of black women also receive lower-quality cancer care after diagnosis, although those differences do not explain the survival gap.
"Something is going wrong," said Dr. Jeffrey H. Silber, a professor at the University of Pennsylvania and the director of the Center for Outcomes Research at the Children's Hospital of Philadelphia, which studies disparities in health care. "These are huge differences. We are getting there too late. That's why we are seeing these differences in survival."
The data show that black patients are twice as likely to never receive treatment. The records of 12.6 percent of black patients did not show evidence of treatment, compared with 5.9 percent of whites.
Black patients were also more likely to have at least a three-month delay in receiving treatment. Among black and white women with similar tumors, 5.8 percent of black women had not started treatment after three months, compared with just 2.5 percent of whites.
One notable finding of the report is that while the introduction of new treatments has improved the outcome for both white and black breast cancer patients since 1991, those improvements have not narrowed the survival gap between the two groups.
But solving disparities in cancer care would not immediately have a major effect on overall survival for black women, the study showed. If black women began receiving exactly the same quality and level of breast cancer treatment as white women, that would lengthen their lives by two to three months, the study showed.
However, two additional years of life could be gained among black women if their breast cancers were detected earlier and if their health were better over all, as is the case with white women with breast cancer. Among the black women studied, 20 percent received a diagnosis of Stage III or IV disease, when the cancer is far less likely to be cured. Among the white women, only 11.4 percent had late-stage disease.
One reason may be that the black women studied were less likely to seek medical care for any reason.
Although all the patients in the analysis had Medicare coverage, blacks were significantly less likely than white women to have seen a primary care doctor in the 6 to 18 months before diagnosis, and they had far lower rates of cholesterol and colon cancer screening. Black women also had far lower rates of breast cancer screening — 23.5 percent had been screened 6 to 18 months before diagnosis, compared with 35.7 percent of white women. Black women with breast cancer were, over all, in poorer health than white women. Of the black women studied, 26 percent had diabetes, compared with 12.6 percent of white women.
"These patients have insurance," Dr. Silber said. "We need to improve screening for these women and improve their relationships with a primary care provider."
In an accompanying editorial, the authors, who included Dr. Jeanne S. Mandelblatt of the Cancer Prevention and Control Program at Georgetown University's Lombardi Cancer Center, said the rigorous study offered "additional clues to the black-white differences in breast cancer outcomes."
However, the authors wrote that the report may still understate the effect of lower-quality cancer care for black women, in part because some treatment data are missing from the database it used.
"Ratings of patient-physician communication and trust have been related to black women's, but not white women's, patterns of chemotherapy use," the authors wrote. These findings further reinforce "the idea that black women may have different cancer care experiences than white women."
