Rise and fall of lung cancers in relation to tobacco smoking and air pollution: A global trend analysis from 1990 to 2012

Lung cancer remains the leading cancer in incidence and mortality in both genders and most countries. Global cancer statistics show a declining trend of lung squamous cell carcinoma (LSCC) but an uprising trend of lung adenocarcinoma (LADC). The reasons behind their opposite trends are unclear. This study aims to analyze the global trends of LSCC and LADC during 1990–2012 in relation to tobacco consumption and air pollution. Results show a 1% decline of smoking prevalence of 7 years ago is associated with a 9% (95% confidence interval: 8%, 10%) drop in the LSCC incidence globally, whereas a 0.1 μg/m3 increment of BC of 7 years ago is associated with a 12% (9%, 16%) increase in LADC incidence globally. Association between BC and LSCC (or LADC) is more prominent in females, with a 14% (7%, 20%) increase in LSCC [or 14% (11%, 19%) increase in LADC] incidence for a 0.1 μg/m3 increment of BC of 8 (or 6) years ago. Associations vary with different genders across different continents. For instance, concentration of BC is positively associated with incidence of both LSCC and LADC in Europe and North America, whereas concentration of sulfate is positively associated with LSCC incidence in Europe and Oceania, and with LADC incidence in Asia, Oceania and South America. We conclude global decreasing LSCC incidence is associated with the reduced tobacco consumption, whereas the global increasing LADC incidence is likely associated with air pollution. Various particulate species have divergent effects on LADC incidence in different continents.