Abstract
BACKGROUND: Lung cancer incidence has been decreasing in the United States, largely due to smoking reductions. However, adenocarcinoma incidence has been relatively stable compared with other histological subtypes. Histology-specific lung cancer incidence varies by key sociodemographic characteristics, but trends are not well characterized. METHODS: SEER 17 registry data was used to calculate annual age-adjusted lung cancer incidence over 2000-2019 by histology stratified by individual-level sex and race/ethnicity and county-level education, poverty, or urbanicity. Histology was categorized into 4 groups: adenocarcinoma, small cell, squamous cell, and other histologies. Age-adjusted incidence rates were computed using the 2000 US Standard Population. Incidence trends were characterized using Joinpoint regression. RESULTS: For most histological subtypes, lung cancer incidence has been decreasing since 2000 in both sexes and all racial/ethnic groups, with some variations. However, lung adenocarcinoma incidence was relatively constant. Lung cancer incidence decreases with increasing education and income. It is lower in urban vs rural areas across histological subtypes, except for adenocarcinoma among females. Counties with higher education levels or lower poverty rates experienced faster declines in small cell and squamous cell lung cancer incidence in recent years. The incidence of small cell and squamous cell lung cancer has been decreasing more rapidly in urban than rural areas. CONCLUSION: Disadvantaged groups have higher lung cancer rates and slower decreases in incidence over time for most histological subtypes, resulting in widening disparities. This highlights the need for targeted tobacco and lung cancer prevention strategies to accelerate decreases in vulnerable populations.