title: Occupational X-ray examinations and lung cancer risk.
abstract: Occupational X-ray examination programs have been conducted in many countries to screen for occupational and nonoccupational respiratory diseases, resulting in widespread exposure to X-radiation. We conducted a multicentre case-control study of lung cancer in the Czech Republic, Hungary, Poland, Romania, Russia and Slovakia, including 2,589 cases and 2,859 controls enrolled during 1998-2002. We collected detailed information on occupational X-ray examinations, occupations and tobacco smoking. We calculated odds ratios of lung cancer via multiple logistic regression after adjustment for age, sex, center and tobacco smoking. Among controls 24.9% reported no X-ray examination, 62.9% reported 1-30 examinations and 12.2% reported more than 30 examinations. When we chose individuals with no examination as the reference group, the odds ratios of lung cancer were 1.21 (95% confidence interval [CI] 0.99-1.48), 1.33 (95% CI 1.08-1.64), 1.49 (95% CI 1.18-1.87), 1.52 (95% CI 1.17-1.99) and 2.15 (95% CI 1.50-3.08) for 1-10, 11-20, 21-30, 31-40 and more than 40 examinations, respectively (p-value of test for linear trend <0.0001). The association between X-ray examinations and lung cancer risk was strong in countries with low prevalence of exposure and absent in countries with high prevalence of exposure. Odds ratios for X-ray examinations were lower among smokers than among nonsmokers. The magnitude of the increased risk observed is higher than expected on the basis of other studies of radiation-exposed populations. Although the association we detected between X-ray examinations and lung cancer risk may reflect a carcinogenic effect of repeated exposure to low-level ionizing radiation, reporting bias and particularly uncontrolled confounding by occupational exposure to carcinogens are also likely explanations of the results.
authors.affiliation: International Agency for Research on Cancer, Lyon, France. boffetta@iarc.it
authors.forename: Paolo
authors.initials: P
authors.lastname: Boffetta
authors.forename: Andrea't
authors.initials: A
authors.lastname: Mannetje
authors.forename: David
authors.initials: D
authors.lastname: Zaridze
authors.forename: Neonila
authors.initials: N
authors.lastname: Szeszenia-Dabrowska
authors.forename: Peter
authors.initials: P
authors.lastname: Rudnai
authors.forename: Jolanta
authors.initials: J
authors.lastname: Lissowska
authors.forename: Eleonóra
authors.initials: E
authors.lastname: Fabiánová
authors.forename: Dana
authors.initials: D
authors.lastname: Mates
authors.forename: Vladimir
authors.initials: V
authors.lastname: Bencko
authors.forename: Marie
authors.initials: M
authors.lastname: Navratilova
authors.forename: Vladimir
authors.initials: V
authors.lastname: Janout
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Cardis
authors.forename: Joelle
authors.initials: J
authors.lastname: Fevotte
authors.forename: Tony
authors.initials: T
authors.lastname: Fletcher
authors.forename: Paul
authors.initials: P
authors.lastname: Brennan
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D005061:Europe, Eastern / Q000453:epidemiology; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000453:epidemiology / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology*; D009784:Occupational Diseases / Q000453:epidemiology / Q000209:etiology*; D016273:Occupational Exposure / Q000009:adverse effects*; D009790:Occupations; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology; D014965:X-Rays / Q000009:adverse effects*