Abstract Ment

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Ethnic and Racial Differences in the Smoking-Related Risk of Lung Cancer

ABSTRACT
Background There is remarkable variation in the incidence of lung cancer among ethnic and racial groups in the United States.
Methods We investigated differences in the risk of lung cancer associated with cigarette smoking among 183,813 African-American,Japanese-American, Latino, Native Hawaiian, and white men and women in the Multiethnic Cohort Study. Our analysis included 1979 cases of incident lung cancer identified prospectively over an eight-year period, between baseline (1993 through 1996) and 2001.
Results The risk of lung cancer among ethnic and racial groups was modified by the number of cigarettes smoked per day. Among participants whosmoked no more than 30 cigarettes per day, African Americans and Native Hawaiians had significantly greater risks of lung cancer than did the other groups. Among those who smoked no more than 10 and those who smoked 11 to 20 cigarettes per day, relative risks ranged from 0.21 to 0.39 (P<0.001) among Japanese Americans and Latinos and from 0.45 to 0.57 (P<0.001) among whites, as compared withAfrican Americans. However, at levels exceeding 30 cigarettes per day, these differences were not significant. Differences in risk associated with smoking were observed among both men and women and for all histologic types of lung cancer.
Conclusions Among cigarette smokers, African Americans and Native Hawaiians are more susceptible to lung cancer than whites, Japanese Americans, and Latinos.
Theincidence of lung cancer is substantially higher among blacks, Native Hawaiians, and other Polynesians and lower among Japanese Americans and Hispanics than among whites in the United States.1 The vast majority (80 to 90 percent) of these cases are attributable to cigarette smoking. Smoking behavior also varies widely among these ethnic and racial groups. In aggregated population surveys conductedin the United States, the age-adjusted prevalence of cigarette smoking was 30.1 percent among black adults and 27.3 percent among white adults.2 Only 8.0 percent of black smokers, however, were reported to be heavy smokers (smoking at least 25 cigarettes per day), as compared with 28.3 percent of white smokers.2 Native Hawaiians had higher rates of lung cancer than whites and Asians in descriptivestudies, even though the smoking habits of these groups were similar.1,3
Previous studies have provided moderate support for the existence of ethnic and racial differences in the smoking-related risk of lung cancer, with black smokers and Native Hawaiian smokers having a greater risk than other populations.4,5,6,7 We examined the relationship between the incidence of lung cancer and smokinghistory among African-American, Japanese-American, Latino, Native Hawaiian, and white men and women in the prospective Multiethnic Cohort Study, focusing on population-based differences in the effects of the extent and duration of smoking and the time since quitting on the risk of lung cancer.
Methods
Study Population
The Multiethnic Cohort Study consists of more than 215,000 men and women inCalifornia and Hawaii and comprises mainly five self-reported racial and ethnic populations: African Americans, Japanese Americans, Latinos, Native Hawaiians, and whites living in Hawaii and California.8 Between 1993 and 1996, adults 45 to 75 years old enrolled in the study by completing a 26-page mailed questionnaire asking detailed information about dietary habits, demographic factors, level ofeducation, occupation, personal behavior, prior medical conditions, and family history of common cancers. Potential participants were identified through driver's license files from the Department of Motor Vehicles, voter registration lists, and Health Care Financing Administration data files.
Incident cancers, histologic types of lung cancer, and the stage of lung cancer were identified by linkage...