Study Cites Geographic Disparities in Lung Cancer Mortality Rates Among Women
According to the American Cancer Society, lung cancer is the leading cause of death among men and women, killing about 84,000 men and 71,000 women each year. Although lung cancer–related death rates in the United States have declined steadily since 1990 in men, they did not start to decline for women until the mid-2000s. However, little is known about recent disparities in progress against lung cancer among women across counties in the United States, where local tobacco control policies, such as smoke-free air laws, are implemented.
To identify clusters of counties that are not benefiting from progress against lung cancer among women, a study was conducted examining county-level changes in lung cancer–related death rates among women between two time periods: 1990–1999 and 2006–2015. The study found that while lung cancer mortality among women in most of the United States has declined substantially, progress among women living in the Midwest and Appalachia has lagged.
Targeted tobacco control programs could reduce the excess burden of lung cancer among women living in these counties and prevent widening geographic inequity. The study by Ross et al is published in Cancer Epidemiology, Biomarkers, & Prevention.
Study Methodology
The researchers obtained county-level lung cancer death rates among women from the National Center for Health Statistics mortality file and calculated relative changes from 1990–1999 to 2006–2015. County-level relative changes in the lung cancer–related death rate were used as input for cluster analysis with optimized hotspot analysis using a software tool called ArcGIS. The distance band used for analysis was identified on the basis of incremental spatial autocorrelation.
To compare mortality in identified hotspots and non-hotspots, the researchers calculated age-standardized rates, rate ratios (RRs), and their 95% confidence intervals (CIs) for each identified hotspot and for the non-hotspot United States for each year between 1990 and 2015.
Study Findings
The researchers identified 2 distinct clusters of counties: 669 in Appalachia and the Midwest (hotspot 1), and 81 in the northern Midwest (hotspot 2). From 1990–1999 to 2006–2015, death rates among women increased by 13% in hotspot 1 and by 7% in hotspot 2 counties, whereas rates decreased by 6% in the non-hotspot United States.
From 1990 to 2015, death rate ratios in hotspot vs non-hotspot counties changed from 4% lower (RR = 0.96, 95% CI = 0.94–0.99) to 28% higher (RR = 1.28, 95% CI = 1.25–1.31) for hotspot 1 counties and from 18% lower (RR = 0.82, 95% CI = 0.76–0.89) to unity (RR = 0.99, 95% CI = 0.93–105) for hotspot 2 counties.
Reducing Lung Cancer Risk
The researchers concluded that targeted tobacco control programs could reduce lung cancer risk among women living in hotspot counties and prevent widening geographic inequity.
“We know that Midwestern and Appalachian states have the highest prevalence of smoking among women and the lowest percent declines in smoking in recent years, so it is perhaps not surprising that we found that women in these areas experienced a disparity in lung cancer death rates,” said Katherine Ross, MPH, a graduate student in the Department of Epidemiology of the Rollins School of Public Health at Emory University and lead author of this study, in a statement. “This geographic disparity may widen unless we specifically aim to reduce tobacco use among women in these hotspots.”
Dr. Ross is the corresponding author of this study.
The study authors reported no conflicts of interest.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
