Cancer risk tied to race of smoker

At half a pack a day, blacks and Hawaiians were far more likely to develop lung cancer

Native Hawaiian and black cigarette smokers with at least a half-pack-a-day habit have a significantly higher risk of lung cancer than smokers who are white, Japanese American or Hispanic, according to a study appearing in today's New England Journal of Medicine.

The study highlights the ethnic differences in smoking-related risks for lung cancer and is useful in helping researchers understand the causes of the disease, said Dr. Loic Le Marchand, a professor at the Cancer Research Center and one of the study's investigators.

The study was conducted by researchers at the University of Hawaii Cancer Research Center and University of Southern California Norris Comprehensive Cancer Center.

"We already know how to prevent it: quit smoking," Le Marchand said.

The study tracked 183,813 smokers in Hawaii and California from 1993 to 1996, with a follow-up questionnaire in 2001. The native Hawaiians, Japanese Americans and whites in the study are from Hawaii, while the blacks and Hispanics are from Los Angeles, Le Marchand said.

During the eight-year span, there were 1,979 cases of lung cancer among the research subjects.

According to the study, blacks who smoked 10 or fewer cigarettes per day were nearly five times as likely to develop lung cancer than Hispanics who smoked the same amount.

At the half-pack daily level, their risk for lung cancer was four times that of Japanese Americans, more than twice as high as whites and only slightly higher than native Hawaiians.

The degree of cancer risk between blacks and the other groups decreased as the number of cigarettes smoked a day increased, except for native Hawaiians, according to the study. For subjects who smoked more than 30 cigarettes per day, the differences between the groups were insignificant, the study said.

Researchers have so far identified genes that might explain why, among Japanese-American smokers, some have a higher risk for lung cancer than others, Le Marchand said.

But they have not yet found an explanation for differences within the other groups or across the different ethnicities, he said.