Socioeconomic differences in lung cancer incidence: a systematic review and meta-analysis

To investigate the associations between various socioeconomic indicators and lung cancer incidence. We searched PubMed and EMBASE databases for studies on socioeconomic position (SEP) and lung cancer incidence published through October 2007. Random-effect model was used to pool the risk estimates from the individual studies. We stratified the analysis by adjustment strategy to investigate the influence of smoking on socioeconomic gradient in lung cancer incidence. Out of 3,288 citations, we identified 64 studies eligible for inclusion. Compared to the highest SEP level, we observed an overall increased risk in lung cancer incidence among people with low educational SEP (61%), low occupational SEP (48%), and low income-based SEP (37%). The negative social gradient for lung cancer incidence remained for most of the possible sets of pooled estimates obtained in subgroup analyses for occupational and educational SEP with less consistency for SEP based on income in studies adjusted and unadjusted for smoking. No evidence of publication bias was apparent. Lung cancer incidence was associated with low educational, occupational, and income-based SEP. The association, adjusted or unadjusted for smoking, points out the importance of social position to be addressed in all discussions on cancer preventive measures.