Journal of the National Cancer Institute Advance Access published online on February 24, 2009
JNCI Journal of the National Cancer Institute, doi:10.1093/jnci/djn513
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© The Author 2009. Published by Oxford University Press.
ARTICLES |
The Role of Smoking and Diet in Explaining Educational Inequalities in Lung Cancer Incidence
Affiliations of authors: The National Institute for Public Health and the Environment, Bilthoven, The Netherlands (GM, HB, FLB, HBB-d-M); Department of Public Health, Erasmus MC, Rotterdam, The Netherlands (GM, AEK); Inserm U687, Villejuif, France (GM); Institute of Cancer Epidemiology, Danish Cancer Society, Copenhagen, Denmark (SOD, OR-N, AT); University of Torino, Torino, Italy (PV); Department of Epidemiology, German Institute of Human Nutrition, Postdam Rehbücke, Germany (MMB); Division of Clinical Epidemiology, German Cancer Research Center, Heidelberg, Germany (SH, RK, JL); International Agency for Research on Cancer, Lyon, France (PF, PB, EJD, NS); Department of Hygiene and Epidemiology, University of Athens Medical School, Athens, Greece (MK, AT, VD); Molecular and Nutritional Epidemiology Unit Cancer Research and Prevention Institute-ISPO, Florence, Italy (DP); Department of Preventive & Predictive Medicine, Nutritional Epidemiology Unit, Italian National Center Institute, Milan, Italy (VK); Department of Clinical and Experimental Medicine, Federico II University, Naples, Italy (SP); Cancer Registry Azienda, Ospedaliera "Civile M.P. Arezzo," Ragusa, Italy (RT); Julius Center for Health Sciences and Primary Care, University Medical Center, Utrecht, The Netherlands (CHvG, PHMP); Institute of Community Medicine, University of Tromso, Tromso, Norway (TB, ITG, EL); Public Health Directorate, Asturias, Spain (LR); Unit of Nutrition, Environment, and Cancer, Catalan Institute of Oncology, Barcelona, Spain (AA); Andalusian School of Public Health, Granada, Spain (M-JS); CIBER Epidemiología y Salud Pública, Spain (M-JS, M-JT, EA); Department of Epidemiology, Murcia Health Council, Murcia, Spain (M-JT); Public Health Institute of Navarra, Pamplona, Spain (EA); Department of Surgery, Malmö University Hospital, Malmö, Sweden (JM); Department of Clinical Sciences, Malmö, Sweden (EW); Nutrition Epidemiology, Lund University, Lund, Sweden (EW); Department of Public Health and Clinical Medicine, Nutritional Research (GH) and Department of Radiation Sciences Oncology (TR), Umeå University, Umeå, Sweden; MRC Center for Nutritional Epidemiology and Cancer Prevention and Survival, Department of Public Health and Primary Care, University of Cambridge, Cambridge, UK (SB, K-TK); Cancer Epidemiology Unit, University of Oxford, Oxford, UK (NA, TK); Department of Epidemiology and Public Health, Imperial College, London, UK (PV, VG, ER)
Correspondence to: Gwenn Menvielle, PhD, Inserm U687, Bat 15/16, Hôpital Paul Brousse, 16 ave Paul Vaillant Couturier, 94807 Villejuif Cedex, France. (e-mail: gwenn.menvielle{at}inserm.fr).
Background: Studies in many countries have reported higher lung cancer incidence and mortality in individuals with lower socioeconomic status.
Methods: To investigate the role of smoking in these inequalities, we used data from 391 251 participants in the European Prospective Investigation into Cancer and Nutrition study, a cohort of individuals in 10 European countries. We collected information on smoking (history and quantity), fruit and vegetable consumption, and education through questionnaires at study entry and gathered data on lung cancer incidence for a mean of 8.4 years. Socioeconomic status was defined as the highest attained level of education, and participants were grouped by sex and region of residence (Northern Europe, Germany, or Southern Europe). Relative indices of inequality (RIIs) of lung cancer risk unadjusted and adjusted for smoking were estimated using Cox regression models. Additional analyses were performed by histological type.
Results: During the study period, 939 men and 692 women developed lung cancer. Inequalities in lung cancer risk (RIImen = 3.62, 95% confidence interval [CI] = 2.77 to 4.73, 117 vs 52 per 100 000 person-years for lowest vs highest education level; RIIwomen = 2.39, 95% CI = 1.77 to 3.21, 46 vs 25 per 100 000 person-years) decreased after adjustment for smoking but remained statistically significant (RIImen = 2.29, 95% CI = 1.75 to 3.01; RIIwomen = 1.59, 95% CI = 1.18 to 2.13). Large RIIs were observed among men and women in Northern European countries and among men in Germany, but inequalities in lung cancer risk were reverse (RIIs < 1) among women in Southern European countries. Inequalities differed by histological type. Adjustment for smoking reduced inequalities similarly for all histological types and among men and women in all regions. In all analysis, further adjustment for fruit and vegetable consumption did not change the estimates.
Conclusion: Self-reported smoking consistently explains approximately 50% of the inequalities in lung cancer risk due to differences in education.
| Context and Caveats Prior knowledge Socioeconomic status is inversely associated with lung cancer incidence and mortality. Study design Relative risk of lung cancer of men and women in the European Prospective Investigation into Cancer and Nutrition study by education level with adjustment for sex, self-reported history of smoking, region of residence, and histological type. Contributions Higher risks of lung cancer in the lowest (vs highest) educated populations were observed among men and women in Northern Europe and among men in Germany. Adjustment for smoking reduced the inequalities in lung cancer risk among men and women in all regions and for all histological types. Implications Adjustment for smoking reduced inequalities in lung cancer risk due to differences in education by approximately 50%. Limitations Smoking history was self-reported, and details such as quantity smoked for ex-smokers were not reported. Other factors, such as exposure to tobacco smoke at home, exposure to pollution, and occupational exposure to carcinogens, were not examined. From the Editors
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Manuscript received July 17, 2008; revised December 1, 2008; accepted December 22, 2008.
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J Natl Cancer Inst 2009 101: 281.
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