Linking urban expansion patterns to lung cancer risk: a nationwide analysis in Chinese cities.

backgroundUrban expansion, with multifaceted urban form changes, has been proved to have profound impact on environmental quality and population health. While existing research has widely explored the link between urban form and respiratory health, most evidence comes from intra-city comparisons within single metropolitan areas, highlighting a need for more representative, nationwide studies.

methodsTo address this gap, we systematically examined associations between urban expansion characteristics and lung cancer incidence across 180 Chinese cities, using structural equation models with air pollution exposure as a mediator.

resultsOur findings indicated that urban expansion characterized by a larger total urban area (β = 0.204, p = 0.014), higher urban population density (β = 0.191, p = 0.004), greater patch density (β = 0.240, p = 0.002), higher annual growth rate (β = 0.266, p < 0.001), and increased urban cropland mixing (β = 0.415, p < 0.001) was associated with higher levels of air pollution exposure, which in turn contributed to elevated lung cancer incidence (β = 0.235, p < 0.001 for females; β = 0.214, p < 0.001 for males). Compared with prefecture-level cities, total urban area, annual growth rate, and urban cropland mixing had a larger marginal impact on lung cancer incidence in county-level cities.

conclusionOur nationwide analysis shows urban expansion characteristics – specifically larger scale, higher density, faster expanding speed, and cropland mixing – significantly elevate lung cancer risk through increased air pollution exposure, with stronger effects in county-level cities. These results provide exploratory evidence that may inform the development of health-oriented urban policies and land use interventions, not only in China but also in other rapidly urbanizing developing countries.