By Rob Stein
Washington Post Staff Writer
Wednesday, July 8, 2009
African Americans are less likely than whites to survive breast, prostate and ovarian cancer even when they receive equal treatment, according to a large study that offers provocative evidence that biological factors play a role in at least some racial disparities.
The first-of-its-kind study, involving nearly 20,000 cancer patients nationwide, found that the gap in survival between blacks and whites disappeared for lung, colon and several other cancers when they received identical care as part of federally funded clinical trials. But disparities persisted for prostate, breast and ovarian cancer, suggesting that other factors must be playing a role in the tendency of blacks to fare more poorly.
For decades, studies have shown that poor people and minorities are more likely to live shorter, sicker lives, and are less likely to survive a host of illnesses, including many cancers. Studies have indicated that the disparities were largely the result of poor people and minorities getting inferior care; they are less likely to have health insurance and receive routine preventive care, they frequently get diagnosed later, and they often undergo less aggressive treatment once they are diagnosed.
The new study is another chance to weigh biology against disparities in the quality of care.
"There is good news and puzzling news in our results," said Kathy S. Albain of Loyola University, whose findings were published online today by the Journal of the National Cancer Institute.
"When there's a level playing field with the same quality of care, African Americans survive just as well as other races from some of our most common cancers, which is reassuring news and points us nationally toward a need to make sure there is quality of care and equal access to all," Albain said. "But for prostate, ovarian and breast [cancer], it's not access to care. There's something else. And we need to sort that out."
Other researchers said the findings were groundbreaking.
"I believe this is a landmark analysis," said Lisa A. Newman of the University of Michigan. "There seems to be something associated with racial and ethnic identity that seems to confer a worse survival rate for African Americans. I think it's likely to be hereditary and genetic factors."
A growing body of evidence has suggested that biological factors may be playing a role in health disparities. Genetic variations, for example, appear to make some therapies more effective or less toxic for some people than others. That idea, however, has been controversial and has raised concern that it could distract from the major cause of disparities, such as poverty, prejudice and geographic variation in quality of care.
Some experts cautioned that the study could not rule out the effects of socioeconomic and environmental factors earlier in life, and expressed worry that the findings could reinforce old prejudices.
"When I hear scientists talking about racial differences, I worry that it starts to harken back to arguments about genetic inferiority," said Otis W. Brawley, chief medical officer of the American Cancer Society and an African American.
In the new study, Albain and her colleagues used data collected from about 19,457 patients between 1974 and 2001 by the Southwest Oncology Group, a National Cancer Institute-funded national cooperative of clinical trials. Because all patients in the studies received the same treatment, if poverty and other socioeconomic factors were to blame, then differences in survival should remain constant across all cancers, the researchers reasoned.
A detailed analysis of the data found no statistically significant association between race and survival for lung and colon cancer -- two of the most common forms of cancer -- or for leukemia, lymphoma and myeloma.
But African Americans were still 49 percent more likely than whites to die from early-stage postmenopausal breast cancer, 41 percent more likely to die from early-stage premenopausal breast cancer, 61 percent more likely to die from advanced ovarian cancer and 21 percent more likely to die from advanced prostate cancer.
Because all the cancers for which the disparity persisted were related to gender, the findings suggest that the survival gap may be the result of a complex interaction of differences in the biology of the tumors and inherited variations in genes that control metabolism of drugs and hormones, Albain said.
Some of the difference in breast cancer survival could be explained by the fact that black women are more likely to get a more aggressive form of the disease that is more difficult to treat. But part of Albain's study and another analysis by researchers at the National Cancer Institute involving more than 244,000 cancer patients nationwide found that could not explain all the difference.
"This is almost certainly related to a mix of factors across races pertaining to tumor biology and inherited factors," Albain said.
Albain disputed suggestions the study could be used to support racial prejudices.
"We certainly aren't talking about 'genetic inferiority' or stereotypes in our study (or implying it) and it would be a shame to have these results misinterpreted by someone in this way," Albain wrote in e-mail. "What we are saying is that there is something that 'tracks' with African ancestry only in these three diseases. . . . Once we discover the explanation for our findings, tailored treatments will benefit all races."
But Brawley, who speaks widely on issues of racial disparity, and others argued that access to high-quality care remains the dominant problem. Socioeconomic factors that occur earlier in life may explain the findings, Brawley said. For example, poor people and minorities are more likely to grow up in polluted neighborhoods and have been hit hardest by the obesity epidemic, which could lead to more difficult-to-treat cancers, he said.
"These differences are not due to inherent genetics. They are due to the effects of environmental factors like diet and exercise and obesity on biology," Brawley said.