July 8, 2009 -- Black women have a lower incidence of breast cancer than white women, but once diagnosed they are more likely to die of the disease. Now, two new studies add to the debate about the roles that access to care and biology play in this disparity.
Poverty and inferior treatment could not explain the poorer survival among black breast cancer patients compared to whites in one of the studies because all the patients received the same treatments as participants in government-sponsored clinical trials.
Black trial participants were also more likely than whites to die of prostate and ovarian cancer, but they were no more likely to die of lung cancer, colon cancer, lymphoma, leukemia, or multiple myeloma.
“The big news here is that for the majority of cancers there is no survival disparity between blacks and whites when access to care is equalized,” lead researcher Kathy S. Albain, MD, of Loyola University tells WebMD.
The fact that this was not the case with the sex-related cancers suggests an important role for as yet unidentified biologic factors, Albain says.
Albain and colleagues analyzed data of nearly 19,500 cancer patients enrolled in 35 clinical trials overseen by the National Cancer Institute (NCI).
“We don’t know what it is, but we know in our study the difference (in mortality) wasn’t related to access to care,” she says. “How could it be access when the access was the same?”
Survival Poorer for Black Women With Breast Cancer
But this biologic difference did not explain the survival advantage among white patients in either the Albain study or new research from the NCI.
Both studies appear in the July 15 issue of the Journal of the National Cancer Institute.
NCI researchers analyzed outcomes for nearly 250,000 breast cancer patients diagnosed between 1990 and 2004.
Black women were significantly more likely than white women to die of their disease, especially in the years immediately following diagnosis, regardless of their estrogen-receptor status.
“We believe this is mostly due to poorer access to care, but you can’t rule out the possibility that biology plays a role,” lead researcher Idan Menashe, PhD, tells WebMD.
American Cancer Society chief medical officer Otis Brawley, MD, tells WebMD that the Albain study is not the first to suggest that poorer access does not completely explain the higher death rate among black patients for sex-related cancers.
Factors Influencing Cancer Survival
But he does not accept Albain’s assertion that there must be genetic or biologic differences between black and white cancer patients that affect cancer survival.
He points out that death rates from breast cancer were the same for black patients and white patients until about 1980.
“In the late 1970s, we started learning how to treat breast cancer,” he says. “Before this time, poverty and access to care would not have had a big impact on survival.”
This is also about the time when obesity began to be a problem in the United States, with the black population affected more than the white population.
In an editorial examining the two studies, Brawley writes that even biologically driven differences in survival between black and white cancer patients may still be influenced by factors such as culture and poverty.
He cites a 2001 study from Scotland that found that poor Scottish women were more likely to have more aggressive estrogen-receptor negative tumors than middle-class or upper-class Scottish women.
“Some biological and even genetic differences in populations are not inherent from birth and immutable,” he writes. “They are influenced by environmental factors associated with socioeconomic status and culture.”
Brawley says the research convinces him that if access to medical care were equal and more emphasis was placed on preventive care, the cancer survival disparity between blacks and whites would largely disappear.
“There are a whole bunch of people out there who are not getting adequate medical care, and it does matter,” he says.