Racial/Ethnic Disparities and Geographic Differences in Lung Cancer Incidence --- 38 States and the District of Columbia, 1998--2006

Lung cancer is the second most commonly diagnosed cancer in both males and females and the leading cause of cancer-related death in the United States (1). Lung cancer affects some races more than others; blacks have higher incidence and mortality rates than do whites (2,3). This report presents the first analysis of lung cancer incidence among racial/ethnic groups by U.S. census region. CDC analyzed data collected by CDC's National Program of Cancer Registries (NPCR) and the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program for the period 1998--2006. These combined data reflect new lung cancer cases representing approximately 80% of the U.S. population. During this study period, annual incidence per 100,000 population was highest among blacks (76.1), followed by whites (69.7), American Indians/Alaska Natives (AI/ANs) (48.4), and Asian/Pacific Islanders (A/PIs) (38.4). Hispanics had lower lung cancer incidence (37.3) than non-Hispanics (71.9). Incidence varied greatly with age, peaking among persons aged 70--79 years (426.7). The region with the highest incidence was the South (76.0); the lowest was the West (58.8). Among whites, the highest lung cancer incidence was in the South (76.3); the highest incidence among blacks (88.9), AI/ANs (64.2), and Hispanics (40.6) were in the Midwest, and the highest incidence among A/PIs was in the West (42.5). These findings identify the racial/ethnic populations and geographic regions that would most benefit from enhanced efforts in primary prevention, specifically by reducing tobacco use and exposure to environmental carcinogens.

Data available from population-based cancer registries affiliated with NPCR, the SEER Program, or both were used in this analysis; new cases of cancer were those reported in NPCR as of January 31, 2009, and in SEER as of November 1, 2008. Data were evaluated according to United States Cancer Statistics (USCS) eligibility criteria.* Thirty-eight states and the District of Columbia met these criteria, representing 79.5% of the U.S. population for the years 1998--2006. Because of the 79.5% population coverage, cancer rates derived from these data are considered to approximate national incidence. Only cancer cases with the primary site of lung or bronchus, according to the World Health Organization's International Classification of Diseases for Oncology, Third Edition, were included in this analysis. Incidence is presented as average annual number of new cases per 100,000 persons. All findings are statistically significant unless otherwise noted. With the exception of age-specific rates, rates are age-adjusted to the 2000 U.S. standard population with 19 age groups.† Adjustments to population data were made by the U.S. Census Bureau to account for the Gulf Coast population in Alabama, Mississippi, Louisiana, and Texas displaced by Hurricanes Katrina and Rita in 2005.§

During 1998--2006, a total of 1,433,172 persons received lung cancer diagnoses (annual incidence: 69.3 per 100,000) in the United States (Table 1). Annual incidence per 100,000 was higher among males (88.2) than females (55.4). Incidence was highest among blacks (76.1), followed by whites (69.7), AI/ANs (48.4), and A/PIs (38.4). Hispanics had lower lung cancer incidence (37.3) than non-Hispanics (71.9). By age group, incidence was highest among persons aged 70--79 years (426.7), followed by ≥80 years (354.8), 60--69 years (258.0), 50--59 years (86.5), 40--49 years (21.8), and <40 years (0.9), a pattern that persisted within racial and ethnic categories (Table 2). Lung cancer incidence was higher among blacks and whites than among AI/ANs or A/PIs for all age groups. When analyzed by U.S. census region,¶ lung cancer incidence was highest in the South (76.0), followed by the Midwest (73.0), Northeast (68.6), and West (58.8) (Figure). Among whites, the highest lung cancer incidence was in the South (76.3); incidence among blacks (88.9), AI/ANs (64.2 [not significant]), and Hispanics (40.6 [not significant]) was highest in the Midwest, and incidence among A/PIs was highest in the West (42.5).

Reported by

TL Fairley, PhD, E Tai, MD, JS Townsend, MS, SL Stewart, PhD, CB Steele, DO, Div of Cancer Prevention and Control, National Center for Chronic Disease Prevention and Health Promotion; SP Davis, PhD, Office on Smoking and Health, National Center for Chronic Disease Prevention and Health Promotion; JM Underwood, PhD, EIS Officer, CDC.

Editorial Note

The findings in this report indicate lung cancer incidence during 1998--2006 was higher in the black population and in persons in the southern United States. However, variation also was observed in lung cancer incidence among racial/ethnic groups by U.S. census region. These findings are consistent with reports indicating a higher incidence among blacks compared with other racial groups (2) and reports showing geographic differences in lung cancer incidence among AI/ANs (4). Racial/ethnic disparities in lung cancer incidence are associated with multiple factors, including differences in smoking prevalence,** metabolism of tobacco smoke products (6), susceptibility to tobacco-induced lung cancer (7), and socioeconomic status (8). Blacks are more susceptible to smoking-induced lung cancer (7) and have less access to health-care services compared with whites.†† These factors might contribute to the higher lung cancer incidence in the black population. Lung cancer also is caused by environmental exposures. Radon, for example, is a naturally occurring, colorless, odorless gas that can become trapped in buildings; it is the second leading cause of lung cancer overall, and the leading cause of lung cancer in nonsmokers.§§

This report presents an analysis of lung cancer incidence in all racial/ethnic groups by U.S. census region. The observed variation in lung cancer incidence by region parallels a reported variation in smoking prevalence across the United States, including higher smoking rates in the South and Midwest and lower rates in the West (9). Regional differences also were observed in smoking prevalence by race/ethnicity, including a higher smoking prevalence among whites in the South, blacks and Hispanics in the Midwest, and A/PIs in the West (9). State comprehensive tobacco control programs, which aim to reduce smoking and tobacco use, can help reduce regional variation of lung cancer incidence.

The findings in this report are subject to at least four limitations. First, USCS data include only 80% of the entire U.S. population and therefore might not accurately represent the whole U.S. population. National estimates of lung cancer incidence might be underreported because many of the states that did not meet data-quality standards¶¶ are in the South, the region with the highest smoking prevalence (9). Despite incomplete U.S. population coverage, combined data from the NPCR and SEER programs provide the best source of information on population-based cancer incidence for the nation, and the only source of information for states having only NPCR-funded cancer surveillance programs. Second, information about smoking status is not available in the cancer registry data. As more complete incidence data become available for all populations in the United States, researchers might be able to further describe patterns of cancer incidence that are specifically related to tobacco use. Third, racial/ethnic data in registries generally are of varying quality for AI/ANs and Hispanics (5). Finally, the distribution of lung cancer histologic types was not considered in this analysis. Although racial differences in histology have been shown in previous studies (3), unpublished analyses by CDC show little variation in lung cancer histology by region or race/ethnicity (CDC, unpublished data, 2010).

Observed variations in lung cancer incidence among racial/ethnic groups likely are influenced by differences in smoking prevalence, exposure to carcinogens, and genetic susceptibility to lung cancer. Tobacco control efforts to prevent initiation and increase cessation have been effective in decreasing lung cancer incidence overall and in narrowing the race-based disparity among young adult smokers (i.e., those aged 20--39 years) (10). A recent CDC report indicates that smoking prevalence varies among racial/ethnic groups, and is highest among persons living below the federal poverty level and those with low educational attainment.*** Use of the U.S. Public Health Service Guidelines for Treating Tobacco Use and Dependence††† is recommended for all persons who use tobacco across the racial/ethnic groups included in this report. Smoking cessation counseling interventions (e.g., quitlines) and medications have been found to be effective cessation interventions in these various populations. CDC also recommends a comprehensive approach to tobacco control, including evidence-based tobacco prevention and cessation strategies.§§§ For example, given that disparities in cigarette use exist, targeted media campaigns should be implemented to reduce social inequalities in smoking and lower the risk for cancer-related morbidity and mortality in minority populations. Enhanced smoke-free laws, and reduced radon exposure also will help decrease lung cancer disparities.¶¶¶ In addition to the implementation of population-based interventions, continued surveillance of lung cancer incidence and smoking prevalence within subpopulations in the United States is warranted.****

References

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5. Clegg LX, Reichman ME, Hankey BF, et al. Quality of race, Hispanic ethnicity, and immigrant status in population-based cancer registry data: implications for health disparity studies. Cancer Causes Control 2007;18:177--87.
6. Wagenknecht LE, Cutter GR, Haley NJ, et al. Racial differences in serum cotinine levels among smokers in the Coronary Artery Risk Development in (Young) Adults study. Am J Public Health 1990;80:1053--6.
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8. Ward E, Jemal A, Cokkinides V, et al. Cancer disparities by race/ethnicity and socioeconomic status. CA Cancer J Clin 2004;54:78--93.
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10. Jemal A, Center MM, Ward E. The convergence of lung cancer rates between blacks and whites under the age of 40, United States. Cancer Epidemiol Biomarkers Prev 2009;18:3349--52.

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