Lung Cancer Hits Certain Races Harder

[GUNNER]

While no one should smoke, it may be even more important for people of certain races to avoid tobacco if they want to prevent lung cancer.

New research suggests that blacks and native Hawaiians who smoke between 10 and 20 cigarettes a day have a 30 percent to 40 percent higher risk of lung cancer than whites do. Latino and Japanese-American smokers had the lowest risk of lung cancer, about 20 percent less than whites and 60 percent less than blacks.

"Lung cancer incidence was higher among African-Americans and Hawaiians," said study author Christopher Haiman, an assistant professor in the department of preventive medicine at the University of Southern California Keck School of Medicine, in Los Angeles.

"But when you're talking about smoking, the message doesn't change; it stays the same. Elimination of smoking will reduce lung cancer incidence," said Haiman, and that's true no matter what your race.

The findings appear in the Jan. 26 issue of the New England Journal of Medicine.

Lung cancer is the deadliest of cancers. Its mortality rate outpaces that of colon, breast and prostate cancers combined. Almost six out of every 10 people with lung cancer die within a year of diagnosis, according to the American Cancer Society. Each year, another 172,000 Americans are diagnosed with the disease, and most of these cancers are attributed to cigarette smoking, the society said.

In past studies, it has been noted that certain racial groups have higher rates of lung cancer than others. One theory is that certain populations are more likely to smoke or smoke more than other groups.

To test that theory, Haiman and his colleagues gathered data from the Multiethnic Cohort Study, from 1993 through 2001. The study included 183,813 men and women who identified themselves as black, white, Latino, Japanese-American or native Hawaiian.

During the eight-year study period, 1,979 people from this group developed lung cancer.

Among men, the rate of current smoking was highest in blacks -- 28.5 percent -- and Hawaiians -- 20.1 percent. For Latino men, the rate was 18.5 percent, and among whites it was 15.9 percent. Japanese-American men had the lowest rates of current smoking at 15.5 percent. In women, blacks (20.5 percent) and Hawaiians (20.2 percent) again had the highest rate of current smoking and Japanese-Americans the lowest (9.3 percent), but more white women (16.3 percent) were current smokers than Latino women (10.3 percent).

Overall, whites, Latinos and Japanese-Americans had significantly lower rates of lung cancer than Hawaiians or blacks, according to the study.

When parsed by smoking levels, the differences remained similar until smoking reached more than 31 cigarettes a day. At that point, the risk of lung cancer began to level out among the groups.

In those who smoked less than 10 cigarettes a day, Hawaiians had a 12 percent reduced risk of lung cancer compared to blacks. Latinos had a remarkable 79 percent reduced risk of lung cancer compared to blacks. For whites, the risk was 55 percent less, and for Japanese-Americans the risk was 75 percent less.

When smoking increased to 11 to 20 cigarettes a day, Hawaiians had a 10 percent lower risk of lung cancer than blacks, while whites had a 43 percent reduced risk. Latinos had a 64 percent lower risk, while Japanese-Americans had a 61 percent decrease in lung cancer risk.

"The differences were more pronounced at lower levels of smoking, but all of these differences were highly statistically significant," said Haiman. "At much higher levels of smoking, these racial and ethnic differences were modest, suggesting some type of saturation level of the carcinogenic effect."

Haiman said the study wasn't designed to tease out the reasons for this effect, but the racial differences could be due to genetic differences in the way nicotine and other chemicals from smoke are metabolized. Or it could be due to differences in smoking behavior, such as one group may be more likely to inhale deeply, he said.

Neil Risch is director of the Institute for Human Genetics at the University of California, San Francisco. He wrote an editorial that accompanied the study.

"There are clearly cases [in disease] where race and ethnicity are important," he said, but this is probably not one of them.

"There's not enough of a difference to specifically target one group and not the other. Lung cancer harms everyone, and everyone should quit smoking," Risch said.