State-Specific Trends in Lung Cancer Incidence and Smoking --- United States, 1999--2008

Lung cancer is the most commonly diagnosed cancer and the leading cause of cancer death in the United States (1). Most deaths from lung cancer are caused by cigarette smoking and exposure to secondhand smoke (2). Large variations in lung cancer (1,3), smoking behavior (4), and tobacco control programs and policies (5,6) have been observed among states. Effective tobacco control policies can decrease smoking prevalence, ultimately leading to decreases in lung cancer (7). To assess lung cancer incidence by state, CDC analyzed data from the National Program of Cancer Registries (NPCR) and the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program for the period 1999--2008. To assess smoking behavior by state, data from the Behavioral Risk Factor Surveillance System (BRFSS) for the period 1994--2009 were analyzed. This report summarizes the results of these analyses. From 1999 to 2008, decreases in lung cancer incidence were observed among men in 35 states and among women in six states. Regionally, the lowest rates and most rapid rate of decline in lung cancer were concentrated among states in the West, correlating with low smoking prevalence and high ratios of former smokers to ever smokers. Further reductions in smoking prevalence are critical to continue the decline in lung cancer incidence.

Data on new cases of invasive lung cancer (International Classification of Diseases for Oncology, Third Edition: C34.0--C34.9) diagnosed during 1999--2008 were obtained from population-based cancer registries affiliated with the NPCR and SEER programs, which, combined, cover all of the U.S. population. Data were evaluated according to United States Cancer Statistics (USCS) data-quality criteria.* Annual incidence rates per 100,000 persons were age-adjusted by the direct method to the 2000 U.S. standard population (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 major population shifts resulting from hurricanes Katrina and Rita in 2005.§ Annual percentage change (APC) was used to quantify the change in incidence rates over time and was calculated using joinpoint regression, which involves fitting a series of joined straight lines on a logarithmic scale to the trends in the annual age-adjusted rates. Up to two joined straight lines were allowed for nationwide and region-specific rates; one straight line was used for state-specific rates. Data from all states and the District of Columbia (DC) met USCS data quality criteria for 2008, but data from only 44 states and three U.S. Census regions (covering 90% of the U.S. population) met these criteria for all years 1999--2008; for this report, APC was calculated only for these states and regions.

Smoking behavior was estimated using results from BRFSS, a state-based surveillance system that collects information on health-risk behaviors, including tobacco use. BRFSS is a random-digit--dialed landline telephone survey of noninstitutionalized civilian adults aged ≥18 years conducted annually in all 50 states, DC, Puerto Rico, Guam, and the U.S. Virgin Islands. Smoking status was determined by asking respondents "Have you smoked at least 100 cigarettes in your entire life?" and "Do you now smoke cigarettes every day, some days or not at all?" Ever smokers were defined as those who reported having smoked at least 100 cigarettes during their lifetime; of these, current smokers were those who reported currently smoking every day or some days and former smokers were those who reported not currently smoking. Quit ratios were calculated as the ratio of former smokers to ever smokers.

The Pearson correlation was used to evaluate the association between lung cancer incidence (1999--2008) and smoking prevalence and quit ratios 5 years prior (1994--2003). Lung cancer rates begin to decline as soon as 5 years after smoking rates decline (6,7). Analyses were weighted by the inverse variances of the age-adjusted rates. All tests of statistical significance were two sided (p<0.05).

Among men, lung cancer incidence continued to decrease nationwide (APC 1999--2005 = -1.4 and APC 2005--2008 = -2.9) (Figure 1). Since 1999, lung cancer incidence among men declined at a faster rate in the West (APC 1999--2006 = -2.3 and 2006--2008 = -3.9) than in other U.S. Census regions. From 1999 to 2008 lung cancer incidence among men decreased in 35 of the 44 states analyzed and remained stable in the other nine states (Figure 2). Many of the states with lowest lung cancer incidence, as well as smoking prevalence, were clustered in the West (Figure 2). The correlation between lung cancer incidence and smoking prevalence 5 years prior was 0.72 (p<0.001). Many of the states with high quit ratios were clustered in the West and Northeast (Figure 2). The correlation between lung cancer incidence and quit ratios 5 years prior was -0.55 (p<0.001).

Among women, lung cancer incidence decreased nationwide (APC 2006--2008 = -2.2) after increasing for years (APC 1999--2006 = 0.5). Lung cancer incidence among women decreased in the West (APC 1999--2006 = -0.5; APC 2006--2008 = -3.7) and stabilized in the Midwest, but was still increasing in the Northeast (APC 1999--2008 = 0.7) (not calculated for the South) (Figure 1). From 1999 to 2008, lung cancer incidence among women decreased in six states (California and Nevada [-1.5%], Washington [-1.0%], Florida and Oregon [-0.9%], and Texas [-0.7%]), remained stable in 24 states, and increased slightly in 14 states (not calculated for six states and DC) (Figure 3). Nearly half of states with higher smoking prevalence for women and more than a third of states with higher lung cancer incidence are in the South (Figure 3). The correlation between lung cancer incidence and smoking prevalence 5 years prior was 0.69 (p<0.0001). High quit ratios among women were clustered among states in the West and Northeast (Figure 3). The correlation between lung cancer incidence and quit ratios 5 years prior was -0.33 (p<0.001).

Reported by

S. Jane Henley, MSPH, Christie R. Eheman, PhD, Lisa C. Richardson, MD, Marcus Plescia, MD, Div of Cancer Prevention and Control, National Center for Chronic Disease Prevention and Health Promotion; Kat J. Asman, MSPH, Shanta R. Dube, PhD, Ralph S. Caraballo, PhD, Timothy A. McAfee, MD, Office on Smoking and Health, National Center for Chronic Disease Prevention and Health Promotion, CDC. Corresponding contributor: S. Jane Henley, shenley@cdc.gov, 770-488-4157.

Editorial Comment

This report documents recent decreases in lung cancer incidence that closely parallel smoking behavior patterns across the United States. States vary substantially in their success at reducing smoking prevalence and lung cancer incidence (1,4). A previous analysis of lung cancer incidence reported that the lowest incidence was in the West and the highest in the South (3). The results of this subsequent analysis demonstrate that lung cancer incidence is decreasing at a faster rate in the West than in other regions of the United States, which corresponds with changes in smoking behavior (1,4).

Since 1999, CDC has recommended and supported state efforts to implement and sustain comprehensive tobacco control programs to discourage smoking initiation, encourage smoking cessation, and protect nonsmokers from secondhand smoke exposure.¶ Decreases in lung cancer incidence and the correlation between lung cancer incidence and quit ratios provide compelling evidence of the value of these tobacco control efforts (1,6). State smoke-free laws continue to be implemented nation-wide, and tobacco excise taxes continue to increase in most, but not all, states (5,8).** In fiscal year 2011, states will collect $25.3 billion from tobacco excise taxes and the tobacco settlement, a 46% increase over the past decade (8). Yet, in the past 3 years, states have cut funding for tobacco control programs by 28% ($199.3 million), and this year states will invest less than 2% of tobacco revenues ($518 million) in tobacco control programs (8). States that invest more fully in these programs, such as California, have experienced decreases in youth and adult smoking prevalence (7--9), decreases in lung cancer (7), and significant health-care savings (8,9).

The findings in this report are subject to at least five limitations. First, not all states met USCS data quality criteria for this period; many of these states were in the South, one of the regions with the highest smoking prevalence. Second, cigarette smoking status is self-reported by BRFSS participants; however, these data have high validity (4). Third, smoking prevalence might be underestimated because BRFSS is a land-line survey and adults with wireless-only service are more likely to smoke cigarettes than the rest of the U.S. population.†† Fourth, BRFSS data are not generalizable to certain populations who are not included in the survey, such as institutionalized persons or persons in the military. Fifth, the majority of lung cancers are caused by cigarette smoking and secondhand smoke exposure; however, lung cancer from other causes, such as other forms of tobacco use or exposure to radon or occupational hazards, might influence geographic variations in lung cancer incidence.

Lung cancer incidence is beginning to decrease among women and is continuing to decrease among men in most states. Variations among states in lung cancer incidence are influenced by variations in smoking behavior. Tobacco control strategies to prevent initiation, accelerate declines in use, and promote cessation have decreased lung cancer incidence among men (1,7) and progress is now being observed among women (10), especially in the West. Lung cancer incidence among women is declining in states with long-running, comprehensive tobacco control programs (8). Tobacco use is an endemic problem and warrants a long-term solution (1,7). Research has shown that the longer and more heavily states invest in comprehensive tobacco control programs, the greater the reduction in smoking and the greater the subsequent savings from reduced smoking-related health costs (8). Research also has shown that any slackening of effort can jeopardize progress.§§ Although great strides in tobacco control and lung cancer incidence reduction have been made, further progress requires intensified efforts to reduce cigarette smoking and secondhand smoke exposure. These efforts depend on adequate funding of tobacco control programs.

Acknowledgment

State and regional cancer registry staffs and Behavioral Risk Factor Surveillance System state coordinators.

References

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