Global socioeconomic inequalities in head and neck cancer

Methods: We pooled individual-level data from case-control studies in the International Head and Neck Cancer Epidemiology (INHANCE) Consortium. Data were available from 23 case-control studies from across the world (18,643 cases and 23,707 controls) providing full information on educational attainment, smoking and alcohol drinking behaviours. We estimated the effect of low relative to high educational attainment on the risk of head and neck cancer overall and by cancer subsite, by calculating pooled odds ratios (ORs) and 95% confidence intervals (95%CI). ORs were adjusted for age, sex, study centre, smoking and alcohol drinking behaviours. We stratified the analysis by sex, global region, and time. We also undertook sensitivity analysis by source of controls (hospital / population-based).

Results: Low relative to high educational attainment was associated with increased risk for head and neck cancer overall OR 1.56 (1.45, 1.67). This finding was tending to be greater among women OR 1.67 (1.43, 1.95) than among men OR 1.51 (1.39, 1.63); and in Latin America OR 1.93 (1.55, 2.40) than in North America OR 1.68 (1.43, 1.98) or in Europe OR 1.28 (1.17, 1.40). The risk was greatest for the hypopharynx subsite OR 3.11 (2.56, 3.79) and lowest for the oropharynx OR 1.36 (1.23, 1.51). The findings were only significant in those who were participants in post-2000 studies and in population-based studies.

Conclusions: The risk for head and neck cancer associated with socioeconomic inequalities varies widely by sex, global region, and cancer subsite. These risks are not totally explained by smoking and alcohol behaviours, and they provide pointers for future aetiological research as well as efforts to plan preventive strategies.