David I. Conway, Darren R. Brenner, Alex D. McMahon, Lorna M.D. Macpherson, Antonio Agudo, Wolfgang Ahrens, Cristina Bosetti, Hermann Brenner, Xavier Castellsague, Chu Chen, Maria Paula Curado, Otávio A. Curioni, Luigino Dal Maso, Alexander W. Daudt, José F. de Gois Filho, Gypsyamber D'Souza, Valeria Edefonti, Eleonora Fabianova, Leticia Fernandez, Silvia Franceschi, Maura Gillison, Richard B. Hayes, Claire M. Healy, Rolando Herrero, Ivana Holcatova, Vijayvel Jayaprakash, Karl Kelsey, Kristina Kjaerheim, Sergio Koifman, Carlo La Vecchia, Pagona Lagiou, Philip Lazarus, Fabio Levi, Jolanta Lissowska, Daniele Luce, Tatiana V. Macfarlane, Dana Mates, Elena Matos, Michael McClean, Ana M Menezes, Gwenn Menvielle, Franco Merletti, Hal Morgenstern, Kirsten Moysich, Heiko Müller, Joshua Muscat, Andrew F. Olshan, Mark P. Purdue, Heribert Ramroth, Lorenzo Richiardi, Peter Rudnai, Stimson Schantz, Stephen M. Schwartz, Oxana Shangina, Lorenzo Simonato, Elaine Smith, Isabelle Stucker, Erich M. Sturgis, Neonila Szeszenia‐Dabrowska, Renato Talamini, Peter Thomson, Thomas L. Vaughan, Qingyi Wei, Deborah M. Winn, Victor Wunsch‐Filho, Guo‐Pei Yu, Zuo‐Feng Zhang, Tongzhang Zheng, Ariana Znaor, Paolo Boffetta, Shu‐Chun Chuang, Marianoosh Ghodrat, Yuan‐Chin Amy Lee, Mia Hashibe, Paul Brennan

Low socioeconomic status has been reported to be associated with head and neck cancer risk. However, previous studies have been too small to examine the associations by cancer subsite, age, sex, global region, and calendar time, and to explain the association in terms of behavioural risk factors. Individual participant data of 23,964 cases with head and neck cancer and 31,954 controls from 31 studies in 27 countries pooled with random effects models. Overall, low education was associated with an increased risk of head and neck cancer (OR = 2·50; 95%CI 2·02- 3·09). Overall one-third of the increased risk was not explained by differences in the distribution of cigarette smoking and alcohol behaviours; and it remained elevated among never users of tobacco and non-drinkers (OR = 1·61; 95%CI 1·13 - 2·31). More of the estimated education effect was not explained by cigarette smoking and alcohol behaviours: in women than in men, in older than younger groups, in the oropharynx than in other sites, in South/Central America than in Europe/North America, and was strongest in countries with greater income inequality. Similar findings were observed for the estimated effect of low vs high household income. The lowest levels of income and educational attainment were associated with more than 2-fold increased risk of head and neck cancer, which is not entirely explained by differences in the distributions of behavioural risk factors for these cancers, and which varies across cancer sites, sexes, countries, and country income inequality levels. © 2014 Wiley Periodicals, Inc.