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Chinese-Americans Absorb Less Nicotine Per Cigarette

Findings may help explain group's lower rate of lung cancer

TUESDAY, Jan. 15, 2002 (HealthDayNews) -- Americans of Chinese descent who smoke absorb less nicotine than their white and Latino counterparts, says new research.

The findings may help explain why lung cancer is less common among Chinese-Americans, and may even affect how smoking cessation therapies are prescribed to people in this ethnic group. Studies have shown that blacks have the highest rates of lung cancer from smoking, followed by whites, Latinos and Chinese-Americans.

Dr. Neal L. Benowitz's group at the University of California, San Francisco, has been studying differences in individual susceptibility to tobacco-related lung cancer.

"Since metabolism of nicotine is thought to influence how much a person smokes, [we thought that] if we looked at metabolic rates in different ethnic groups that it might provide one clue as to different exposures to tobacco smoke," says Benowitz.

Benowitz's team studied 37 Chinese-Americans, 40 Latinos and 54 white volunteers from the San Francisco Bay area. The smoking habits of each volunteer reflected the national average for their ethnic group.

The first clue lay in cigarette consumption. Chinese-Americans, followed by Latinos, appear to smoke fewer cigarettes, says Benowitz.

Moreover, this latest study found that Chinese-Americans take in 35 percent less nicotine per cigarette, compared to white people. Previous studies found that blacks take in between 30 and 40 percent more nicotine per cigarette than do whites.

The findings appear in tomorrow's issue of the Journal of the National Cancer Institute.

Benowitz says Chinese-Americans appear to smoke less intensively, taking in less of the nicotine and corresponding cancer-causing chemicals in tobacco smoke. Chinese-Americans also appear to take in less smoke per cigarette.

"Chinese-Americans have a lower risk [of lung cancer] per cigarette," says Benowitz.

The researchers also studied the metabolic pathway for nicotine. They found Chinese-Americans have less of an enzyme called CYP2A6, which breaks down nicotine and activates some of the cancer-causing chemicals in tobacco smoke.

"The fact that Chinese-Americans have lower levels of this enzyme means they metabolize nicotine more slowly and, also, they activate carcinogens more slowly," says Benowitz. "We think it's another reason why Chinese-Americans have lower lung cancer rates. We should be looking at factors like these for cancer risk in general."

The report notes nicotine isn't the only drug that is metabolized differently by certain ethnic groups. For example, says Benowitz, Asians metabolize alcohol differently than do people from other ethnic backgrounds.

Karen Ahijevych, co-director of the Nursing Center for Tobacco Intervention at the Ohio State University College of Nursing, is familiar with the study.

"It's not uncommon that something like nicotine might be processed differently by different ethnic groups," she says.

One potential implication of these different rates of nicotine metabolism is that people from certain ethnic groups may require different doses of nicotine during smoking cessation therapy.

"When people buy nicotine products over the counter, it would be important to at least modify the amount that they would use if they know that Chinese-Americans…would use a lower dosage," says Ahijevych. "They may start at a lower dose, and see if that helps to manage their cravings."

Benowitz says this idea works in theory, but since people can tolerate a wide range of nicotine doses without getting sick, it may not have practical implications. Still, he says it may be worth studies to determine the best dose for Asian populations.

However, Benowitz stresses Chinese-Americans should not develop a false sense of security about smoking because they have a lower risk of lung cancer than other groups.

"A white smoker is 20 times more likely to develop lung cancer than a nonsmoker," says Benowitz. "An Asian smoker is five times more likely than a nonsmoker to develop cancer. That's better odds, but it's still not great odds."

What To Do

Check out this paper on nicotine metabolism that Ahijevych wrote for a National Institute on Drug Abuse conference. You can also read this Centers for Disease Control and Prevention report on tobacco use among U.S. racial and ethnic minority groups.

Need advice on quitting smoking? Visit the American Lung Association. Older smokers can take this quiz from the National Heart, Lung and Blood Institute.

SOURCES: Interviews with Neal L. Benowitz, M.D., clinical pharmcologist, professor of medicine, Division of Clinical Pharmacology and Experimental Therapeutics, Departments of Medicine, Psychiatry and Biopharmaceutical Sciences, University of California, San Francisco; Karen Ahijevych, Ph.D., R.N., co-director, Nursing Center for Tobacco Intervention, College of Nursing, Ohio State University, Columbus, Ohio; Jan. 16, 2002, Journal of the National Cancer Institute
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