How much do smoking and alcohol consumption explain socioeconomic inequalities in head and neck cancer risk? A F Boing, 1 J L Ferreira Antunes, 2 M Brasilino de Carvalho, 3 J Francisco de Go ´is Filho, 4 L P Kowalski, 5 P Michaluart Jr, 6 Head and Neck Genome Project/GENCAPO 7 J Eluf-Neto, 8 P Boffetta, 9 V Wu ¨nsch-Filho 10 ABSTRACT Background A higher burden of head and neck cancer has been reported to affect deprived populations. This study assessed the association between socioeconomic status and head and neck cancer, aiming to explore how this association is related to differences of tobacco and alcohol consumption across socioeconomic strata. Methods We conducted a case-control study in Sa ˜o Paulo, Brazil (1998e2006), including 1017 incident cases of oral, pharyngeal and laryngeal cancer, and 951 sex- and age-matched controls. Education and occupation were distal determinants in the hierarchical approach; cumulative exposure to tobacco and alcohol were proximal risk factors. Outcomes of the hierarchical model were compared with fully adjusted ORs. Results Individuals with lower education (OR 2.27; 95% CI 1.61 to 3.19) and those performing manual labour (OR 1.55; 95% CI 1.26 to 1.92) had a higher risk of disease. However, 54% of the association with lower education and 45% of the association with manual labour were explained by proximal lifestyle exposures, and socioeconomic status remained significantly associated with disease when adjusted for smoking and alcohol consumption. Conclusions Socioeconomic differences in head and neck cancer are partially attributable to the distribution of tobacco smoking and alcohol consumption across socioeconomic strata. Additional mediating factors may explain the remaining variation of socioeconomic status on head and neck cancer. Tumours of the oral cavity, pharynx and larynx, taken together as head and neck cancer (HNC), have a high incidence worldwide and take a high toll on mortality in developing countries. The global burden of HNC accounts for 650 000 new cases and 350 000 deaths worldwide every year. 1 The city of São Paulo, the location of the current study, experiences a particularly high incidence of HNC, which corresponds to 11% of all new cancer cases (not including non-melanoma skin cancer) among men and 2.8% among women. 2 With more than 10 million inhabitants, this is one of the largest cities in Latin America and capital of the most populous and industrialised Brazilian state. Throughout the last decades, São Paulo experienced relevant improvements in life expectancy and health indicators. 3 Notwithstanding, intense inequalities affect the population and affluent and deprived socioeconomic strata co-habit the town, resembling patterns of heterogeneous socioeco- nomic conditions at the country level. More than 70% of squamous cell carcinoma of the head and neck are estimated to be avoidable by lifestyle changes, particularly by effective reduction of exposure to well-known risk factors such as tobacco smoking and alcohol drinking. 4 Ecological and individual-based studies conducted in several countries have reported higher incidence and mortality by HNC in deprived populations. 5 In addition, patients with lower education and non- professional occupations usually exhibit a poorer prognosis and lower survival rates. 6 A recent meta- analysis on socioeconomic inequalities and oral cancer risk concluded that public health strategies should advocate for socioeconomic change in addi- tion to behaviour change. 7 However, the concurrent association of socio- economic status (SES) with the risk of HNC and with proximal behavioural risk factors has been scarcely assessed and produced inconclusive results. A critical question related to this subject refers to what extent the variation of smoking and alcohol consumption across social strata could explain socioeconomic differences in the incidence of HNC. Previous studies which have investigated tobacco smoking and alcohol consumption as covariates of cancer incidence did not explain the concurrent relationship of socioeconomic position with prox- imal risk factors and with disease outcome. 8 9 However, recent studies 10 11 have assessed the aetiological chain of HNC using a conceptual framework of covariates that organises distal socioeconomic and proximal behavioural determi- nants, a strategy aimed at instructing initiatives to reduce both cancer incidence and socioeconomic inequalities in health. This study aimed to explore the extent to which differences of tobacco smoking and alcohol consumption across socioeconomic strata explain the association between SES and HNC in a large database of patients in the city of São Paulo, Brazil. METHODS Participants This is a hospital-based case-control study involving newly diagnosed patients with HNC and hospital controls participating in two broader multicentre studies: the Latin-American section of the “International study of environment, viruses and cancer of the oral cavity and the larynx” 12 and 1 Centro de Cie ˆncias da Sau ´de, Universidade Federal de Santa Catarina, Floriano ´polis, Santa Catarina, Brazil 2 Faculdade de Odontologia, Universidade de Sa ˜o Paulo, Sa ˜o Paulo, Brazil 3 Hospital Helio ´polis, Secretaria de Estado da Sau ´de de Sa ˜o Paulo, Sa ˜o Paulo, Brazil 4 Instituto do Ca ˆncer Arnaldo Vieira de Carvalho, Sa ˜o Paulo, Brazil 5 Hospital do Ca ˆncer A.C. Camargo, Sa ˜o Paulo, Brazil 6 Hospital das Clı ´nicas, Faculdade de Medicina, Universidade de Sa ˜o Paulo, Sa ˜o Paulo, Brazil 7 See appendix 8 Faculdade de Medicina, Universidade de Sa ˜o Paulo, Sa ˜o Paulo, Brazil 9 International Agency for Research on Cancer, Lyon, France 10 Faculdade de Sau ´de Pu ´blica, Universidade de Sa ˜o Paulo, Sa ˜o Paulo, Brazil Correspondence to Jose ´ Leopoldo Ferreira Antunes, Escola de Artes, Cie ˆncias e Humanidades, Universidade de Sa ˜o Paulo, 1000 R Arlindo Be ´ttio, sala 81-A1, Sa ˜o Paulo 03828-900, Brazil; leopoldo@usp.br Complete author list and addresses presented in the Appendix. Accepted 21 February 2010 Published Online First 18 August 2010 J Epidemiol Community Health 2011;65:709e714. doi:10.1136/jech.2009.097691 709 Research report