Declines in Lung Cancer Rates-California, 1988-1997

Cigarette smoking is the leading cause oflung and bronchus cancer. During 1988-1997, per capita cigarette smoking inCalifornia declined more than twice as rapidly as it did in the rest of thecountry. To characterize lung cancer incidence in California, data from theNational Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER)program were compared with data from the population-based California CancerRegistry. This report summarizes the results of that analysis, which indicatedthat during 1988-1997, age-adjusted lung cancer incidence rates in Californiadeclined significantly, compared with stable incidence rates for the combinedSEER area of five states and three metropolitan areas.

The SEER data used in the analysis were from Connecticut,Hawaii, Iowa, New Mexico, and Utah, as well as Atlanta, Detroit, and the Seattle-PugetSound area. The SEER registries in California were excluded from the SEERanalysis and were included with the California Cancer Registry data. (CaliforniaCancer Registry data were statewide; the SEER data collected in Californiaincluded Los Angeles and the San Francisco Bay area only.)

Cancer incidence rates were age-adjusted by the direct methodbased on estimated 2000 US population data. Annual lung and bronchus cancerincidence rates per 100,000 population during 1988-1997 were reported amongmen, women, and both sexes combined for California and the eight SEER regionscombined (Table 1). Two measures of change were reported. First, the estimatedannual percentage change (EAPC) was calculated using the average percentageincrease or decrease in cancer incidence rates per year during 1988-1997, anda regression line was fitted using the assumption that the natural logarithm ofcancer rates changed at a constant rate during the 10-year period. Second, thetotal percentage change was the average of 1988 and 1989 data minus the averageof 1996 and 1997 data divided by 1988 and 1989 data and multiplied by 100.Statistical significance was set at alpha = .01 (Figure 1).

Non-California SEER data did not reveal a consistent pattern inthe age-adjusted lung and bronchus cancer incidence rates during 1988-1997. AnEAPC of -0.4% per year was not significantly different from 0. Comparing theCalifornia Cancer Registry incidence rates with non-California SEER incidencerates, the California lung and bronchus cancer incidence rates were slightlyhigher during 1988-1990 (Table 1). However, during 1991-1997, incidencerates in California declined from 68.0 per 100,000 to 60.1. During 1988-1997,overall lung and bronchus cancer California incidence rates decreased an averageof 1.9% per year (P < .01, Figure 1). The California incidencerates decreased 14.0% during the 10-year period; the rates in non-CaliforniaSEER regions decreased 2.7%.

The decline in incidence rates among men (all ages combined) inthe California data was 1.5 times greater than the decline among men in thenon-California SEER regions. Among men, lung and bronchus cancer incidence ratesdeclined significantly during 1988-1997 in data from California and the SEERregions; however, the decline was greater in California (EAPC = -2.9%; P <.01) compared with non-California SEER regions (EAPC = -1.8%; P < .01).Among women (all ages combined) in California, lung and bronchus cancerincidence rates declined 4.8% during 1988-1997 (EAPC = -0.6; P < .01);incidence rates among women in non-California SEER regions increased 13.2% (EAPC= 1.5; P < .01).

Reported by: D.W. Cowling, PhD; S.L. Kwong, MPH; R. Schiag,MS;J.C. Lloyd, MA; D.G. Bal, MD; Tobacco Control Section and Cancer SurveillanceSection; California Department of Health Services; Office on Smoking and Health;National Center for Chronic Disease Prevention and Health Promotion; Centers forDisease Control and Prevention (CDC).

Editorial Note From the CDC

More than 80% of lung and bronchus cancer is caused by cigarettesmoking, and former smokers have about half the risk of dying from lung cancerthan do current smokers. Compared with current smokers, the risk for lung andbronchus cancer among former smokers declines as the duration of abstinencelengthens, with risk reduction becoming evident within 5 years of cessation.Reductions in the smoking rate in a state could reduce lung and bronchus cancerrates within 5 years of the decline in smoking rates.

The difference in the rate of decline in lung and bronchuscancer incidence rates between California and other US regions may be related,in part, to the significant declines in smoking rates as a result of Californiatobacco control initiatives. The California Tobacco Control Program was createdby Proposition 99 and was approved in 1988. The program emphasized acomprehensive approach to tobacco control, prevention, and education andincluded strategies to change social norms related to tobacco use.

The decrease in per capita cigarette consumption that began in1990 has been attributed to the $0.25 increase in the excise tax in 1989. During1988-1996, California had a more rapid decline in per capita cigaretteconsumption compared with the rest of the country. This decline has beenattributed primarily to a change in the social acceptability of smoking amongCalifornia residents. However, smoking rates in California were declining morerapidly than the rest of the country since the late 1980s, before enactment ofProposition 99.

Study Limitations

The findings in this study are subject to at least threelimitations. First, the SEER cancer incidence rates are based on data fromselected geographic areas and may not represent incidence rates nationally; SEERdata in this analysis represent 9.5% of the US population (excludingCalifornia). Second, although a constant rate of change over the study period isthe standard assumption when using the EAPC, this assumption has not beentested. Third, although decreased population smoking rates in California areprobably responsible for reduced rates of lung and bronchus cancer, acause-and-effort relation cannot be determined through population-basedassessments.

Programs in Other States

Following the California model, aggressive and comprehensivetobacco-control programs have been implemented in other states, includingArizona, Florida, Maine, Massachusetts, and Oregon. Initial results from severalstates have shown substantial declines in per capita cigarette consumptionand/or changes in the prevalence of adult or youth smoking rates. The results ofthis report suggest that a comprehensive tobacco prevention and educationprogram may also reduce rates of lung and bronchus cancer.

On the basis of results from state programs, the CDC publishedthe Best Practices for Comprehensive Tobacco Control. This document, along withthe release of the Surgeon General’s Report, Reducing Tobacco Use: A Report ofthe Surgeon General, provides guidance to states in establishing successful andsustainable tobacco control programs.