Race May Be Factor In Lung Cancer
Thursday, January 26, 2006
Blacks are much more likely than whites to get lung cancer from smoking cigarettes, according to a large study that provides significant new evidence in the debate over whether race plays an important role in health.
The eight-year study of more than 183,000 people found that blacks and ethnic Hawaiians are about 55 percent more likely than whites to develop lung cancer from light to moderate smoking. Japanese Americans and Latinos are about 50 percent less likely than whites, the researchers found.
Although previous studies have indicated that smoking poses varying degrees of risk to people from different racial and ethnic backgrounds, the size and sophistication of the study, being published in today's issue of the New England Journal of Medicine, make it the most convincing to date, the researchers said.
"We observed quite striking differences," said Christopher A. Haiman of the University of Southern California, who led the study. "This suggests there are racial and ethnic differences in the smoking-related risk of lung cancer."
The study rekindles a long-running and emotional debate about whether race is important in understanding why some people are more prone to certain diseases, whether treatments should be tailored to racial and ethnic groups, and whether biological differences help explain why racial minorities are so much more likely than whites to get sick, respond less well to treatment and die younger.
Proponents of the importance of racial differences hailed the findings as strong evidence that biological differences among races can be significant, making it imperative that research focus on these genetic variations to try to resolve stubborn disparities in health.
"If this happens with tobacco, what about other drugs? Tobacco is a drug. What about the drugs we give to patients, such as cancer medications or heart medications or lung medication?" asked Esteban Gonzalez Burchard of the University of California at San Francisco. "There could be important biologic differences that help to explain the differences we see in disease prevalence, severity and mortality, as well as response to therapies."
Skeptics, however, said that the study is inconclusive and that it could fuel racial stereotyping and divert attention from environmental and social factors that are probably far more important.
"This feeds into the 19th-century notion that these categories really separate people in terms of their physical and biological characteristics," said Troy Duster of New York University. "The reason why black people may be getting cancer more has to do with a combination of forces, not just their biologic makeup."
Haiman and his colleagues analyzed data collected from 183,813 adults in California and Hawaii as part of the federally funded multiethnic cohort study. Although its main purpose was to examine the relationship between diet and health, researchers also collected detailed information about the participants' smoking.
When Haiman and his colleagues analyzed the risk for lung cancer over an eight-year period, they found that blacks and native Hawaiians who smoked less than about a pack of cigarettes a day were about 40 to 55 percent more likely than whites to develop lung cancer. Latinos and Japanese Americans who smoked that much were about 30 to 50 percent less likely. The differences disappeared among those who smoked more than that, probably because the toxicity of smoking at high levels overwhelmed other factors, Haiman said.
The differences persisted even after researchers considered factors such as diet, socioeconomic status and occupation.
Although the study could not rule out the possibility that the findings were the result of some unidentified environmental differences, it could be that blacks tended to be biologically predisposed to react differently to nicotine or to the cancer-causing chemicals in tobacco smoke, Haiman said.
"There may be differences in how they metabolize nicotine, which would influence smoking behaviors such as the depth and frequency of inhalation of tobacco smoke," Haiman said. "There could be genetic factors on how they metabolize tobacco smoke."
Jeffrey Kahn, a bioethicist at the University of Minnesota, said he worries that the findings could be used to further discriminate.
"The danger would be to sort of view lung cancer as a minority disease, and so something we don't have to worry as much about," Kahn said.
But M. Gregg Bloche of Georgetown University said the findings should spur more research to understand the relative roles of genetics, biology, social conditions and environmental factors.
"The biggest danger here is ideology on both sides getting in the way of trying to understand this phenomenon," he said.