Multiethnic Cohort Study Update on Racial/Ethnic Differences in Lung Cancer Incidence
In an update from the Multiethnic Cohort Study reported in the Journal of the National Cancer Institute, Stram et al found persistent racial/ethnic differences in risk for lung cancer at similar levels of cigarette smoking intensity. A prior report from the study found that African Americans and Native Hawaiians were at highest lung cancer risk compared with Japanese Americans, with whites having intermediate risk. The differences were more evident at relatively low levels of smoking intensity (eg, ≤ 20 cigarettes per day) vs higher levels of intensity).
Estimated Excess Relative Risks
The update included 4,933 cases of lung cancer. Estimated excess relative risks for smokers vs nonsmokers for all lung cancers after accumulation of 25 pack-years due to smoking for 50 years at 10 cigarettes per day were 21.9 among Native Hawaiians, 19.1 among African Americans, 11.9 among whites, 10.1 among Japanese Americans, and 8.0 among Latinos. Estimated excess relative risks after accumulation of 50 pack-years at 20 cigarettes per day were 35.3 among Native Hawaiians, 31.7 among African Americans, 24.0 among whites, 21.4 among Japanese Americans, and 20.0 among Hispanics. The risk associated with smoking was higher for squamous cell carcinomas and small cell cancers than for adenocarcinomas.
In a study using a urinary biomarker expressed in terms of total nicotine equivalents, adjustment for total nicotine equivalents showed that Japanese Americans no longer exhibited a lower risk and African Americans no longer exhibited a higher risk compared to whites. A marked risk difference between Native Hawaiians and Latinos persisted in the analysis.
The investigators concluded, “Racial differences in lung cancer risk persist in the Multiethnic Cohort study that are not easily explained by variations in self-reported or urinary biomarker-measured smoking intensities.”
Daniel O. Stram, PhD, of the Department of Preventive Medicine, Keck School of Medicine, University of Southern California, is the corresponding author for the Journal of the National Cancer Institute article.
Disclosure: The study was supported by the National Cancer Institute. The study authors' full disclosures can be found at academic.oup.com.
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