title: Residential radon exposure, histologic types, and lung cancer risk. A case-control study in Galicia, Spain.
abstract: BACKGROUND
  Lung cancer is an important public health problem, and tobacco is the main risk factor followed by residential radon exposure. Recommended exposure levels have been progressively lowered. Galicia, the study area, has high residential radon concentrations. We aim (i) to assess the risk of lung cancer linked to airborne residential radon exposure, (ii) to ascertain whether tobacco modifies radon risk, and (iii) to know whether there is a lung cancer histologic type more susceptible to radon.
  
  
  METHODS
  A hospital-based case-control design was conducted in two Spanish hospitals. Consecutive cases with histologic diagnosis of lung cancer and controls undergoing trivial surgery not tobacco-related were included. Residential radon was measured using standard procedures. Results were obtained using logistic regression.
  
  
  RESULTS
  Three hundred and forty-nine cases and 513 controls were included. Radon exposure posed a risk even with a low exposure, with those exposed to 50 to 100 Bq/m(3) having an OR of 1.87 [95% confidence interval (CI), 1.21-2.88] and of 2.21 (95% CI, 1.33-3.69) for those exposed to 148 Bq/m(3) or more. Tobacco increased appreciably the risk posed by radon, with an OR of 73 (95% CI, 19.88-268.14) for heavy smokers exposed to more than 147 Bq/m(3). Less frequent histologic types (including large cell carcinomas), followed by small cell lung cancer, had the highest risk associated with radon exposure.
  
  
  CONCLUSIONS
  The presence of airborne radon even at low concentrations poses a risk of developing lung cancer, with tobacco habit increasing considerably this risk.
  
  
  CONCLUSIONS
  Public health initiatives should address the higher risk of lung cancer for smokers exposed to radon.
authors.affiliation: Department of Preventive Medicine and Public Health, University of Santiago de Compostela, Santiago de Compostela, Spain.
authors.forename: Juan Miguel
authors.initials: JM
authors.lastname: Barros-Dios
authors.forename: Alberto
authors.initials: A
authors.lastname: Ruano-Ravina
authors.forename: Mónica
authors.initials: M
authors.lastname: Pérez-Ríos
authors.forename: Margarita
authors.initials: M
authors.lastname: Castro-Bernárdez
authors.forename: Jose
authors.initials: J
authors.lastname: Abal-Arca
authors.forename: Marta
authors.initials: M
authors.lastname: Tojo-Castro
mesh_terms: D000230:Adenocarcinoma / Q000453:epidemiology* / Q000473:pathology; D000077192:Adenocarcinoma of Lung; D000368:Aged; D002274:Carcinogens, Environmental / Q000032:analysis; D016022:Case-Control Studies; D004781:Environmental Exposure / Q000032:analysis*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000453:epidemiology* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011886:Radon / Q000032:analysis*; D018570:Risk Assessment; D012307:Risk Factors; D013030:Spain / Q000453:epidemiology
chemical_list: D002274:Carcinogens, Environmental; D011886:Radon