Smoking, alcohol drinking, occupational exposures and social inequalities in hypopharyngeal and laryngeal cancer

Background Social inequalities with regard to hypopharyngeal and laryngeal cancers are observed in many countries. Differences in alcohol and tobacco consumption are often proposed as an explanation for this finding. The aim of this work was to determine the extent to which alcohol and tobacco consumption, and occupational exposure, explain these inequalities. Methods A hospital-based case-control study included 504 male cases (105 with glottic, 80 with supraglottic, 97 with epilaryngeal, and 201 with hypopharyngeal cancers) and 242 male controls with non-respiratory cancers. Information about sociodemographic characteristics, detailed alcohol and tobacco consumption, educational level, and occupational history were collected. Odds ratios (OR) and their 95% CI were computed using logistic regressions. Results When controlling for age only, laryngeal and hypopharyngeal cancers were strongly associated with educational level (OR for low versus high level = 3.22, 95% CI: 2.01, 5.18) and with all indicators based on occupation (OR for ever versus never manual worker = 2.54, 95% CI: 1.78, 3.62). When adjusted for alcohol and tobacco consumption, the OR decreased, but remained significant for occupation (OR for ever manual worker = 1.91, 95% CI: 1.23, 2.95). After further adjustment for occupational exposures, significant associations were no longer observed. Associations differed between subsites. Conclusions Social inequalities observed for these cancers are not totally explained by alcohol and tobacco consumption; a substantial proportion could be attributable to occupational exposures.