Smoker's race plays a role in lung cancer

Washington -- New findings are adding to evidence that racial and ethnic differences matter when it comes to smoking and lung cancer.

A study in the Jan. 26 New England Journal of Medicine indicates that African-American and Native Hawaiian smokers face a significantly greater risk of lung cancer than do smokers who are white, Japanese-American or Hispanic.

Whites, in turn, have a greater risk than do Japanese-Americans and Hispanics, said study author Christopher Haiman, ScD, assistant professor in the Dept. of Preventive Medicine at the University of Southern California in Los Angeles. The rates were similar for men and women.

A second study, in the January issue of Ethnicity and Disease, found that some of the already recognized ethnic and racial differences that underlie how adults' metabolize nicotine are also at work in teens.

The new studies add to an ongoing debate over genetics and race and their implications for medical care. The debate was advanced last summer with the approval of BiDil, the medication for heart failure, which had been found to be more effective among black patients than white.

"It is difficult to discuss the role of genetics in differences among groups, because of the fear that such discourse may reinforce notions of biologic determinism," noted Neil Risch, PhD, director of the Institute for Human Genetics at the University of California, San Francisco, in an editorial on Dr. Haiman's study.

Some insist that racial and ethnic categories are social, with little relevance to genetics, Dr. Risch said. But recent studies say genetic markers correlate strongly with identification with racial and ethnic groups, he noted.

This seems to be the case with smoking.

Dr. Haiman found that the risk of lung cancer among the 183,813 smokers studied was modified by the number of cigarettes they smoked. Among participants who smoked 10 cigarettes per day, African-Americans and Native Hawaiians had a significantly greater risk of lung cancer than did other groups.

But differences between the groups studied nearly disappeared when participants smoked 30 or more cigarettes daily. "This suggests that whatever the factors are that are contributing to these differences, they might have a more dramatic role in lower levels of smoking," Dr. Haiman said.

He speculated that the disappearance of differences among heavy smokers might be explained by the saturation of the pathways involved in metabolizing tobacco carcinogens.

Earlier studies demonstrated that racial and ethnic differences do exist in the metabolism of tobacco carcinogens. And research findings in Ethnicity and Disease by scientists with the National Institute on Drug Abuse suggest that those underlying differences are at work in teens.

NIDA scientists measured the ratio of the nicotine-breakdown product cotinine to the number of cigarettes smoked per day. They found that although black teens smoked fewer cigarettes per day -- 15.1 cigarettes vs. 19.6 for white youth -- white and black adolescents exhibited similar measures of nicotine dependence and blood cotinine concentrates.

The significantly higher ratio of cotinine to cigarettes smoked per day among black teens helped confirm this slower metabolism rate, according to the researchers.

The results also might affect how teens of different racial and ethnic backgrounds are counseled on quitting. "These findings may constitute a strong warning to black youth to keep from smoking in the first place," said NIDA Director Nora D. Volkow, MD. "They may also explain why certain smoking cessation therapies work better in some populations than in others, and therefore, which treatments should be offered to which teens." For example, black teens might not be offered cessation therapies if the treatments are provided on the basis of how many cigarettes are smoked each day, she said.

The message that everyone should stop smoking is clear, Dr. Haiman said. "Whether you're smoking one or 10 or 20 or 30 [cigarettes], you shouldn't smoke any." That is also the message from the Lung Cancer Alliance, which issued on Jan. 19 a "Report Card on Lung Cancer." The group handed out failing grades on the nation's efforts.

The number of lung cancer deaths is unacceptable, receiving an F. Lung cancer is the No. 1 cancer killer, killing three times as many men as prostate cancer and twice as many women as breast cancer, according to the group. Another F was given for the poor long-term survival rate of people with lung cancer. Only 15% of those diagnosed live longer than five years. In contrast, breast cancer's five-year survival rate is 88%, and prostate cancer's is 99%, the alliance noted.

In addition, F's were given for:

• Lack of progress in diagnosis. Seventy percent of diagnoses are at late stages.
• The 2,000 new daily smokers younger than 18 added each day.
• The lack of federal support for early screening.
• The low funding level for research.

The best grade the group handed out was a D for the number of treatments and diagnostic options developed in the past 30 years.