Residential radon exposure, histological types and lung cancer risk. A case-control study in Galicia, Spain
Menée en Espagne, cette étude cas-témoins (349 cas et 513 témoins) évalue l'association entre une exposition domestique au radon, le comportement tabagique, le type histologique et le risque de cancer du poumon
Background: Lung cancer is an important public health problem and tobacco 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: 1) to assess the risk of lung cancer linked to airborne residential radon exposure, 2) to ascertain whether tobacco modifies radon risk and, 3) to know whether there is a lung cancer histological type more susceptible to radon. Methods: A hospital-based case-control design was performed in two Spanish hospitals. Consecutive cases with histological 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: 349 cases and 513 controls were included. Radon exposure posed a risk even with a low exposure, with those exposed to 50-100 Bq/m3 having an OR of 1.87 (CI95% 1.21-2.88) and of 2.21 (CI 95% 1.33-3.69) for those exposed to 148 Bq/m3 or more. Tobacco increased appreciably the risk posed by radon, with an OR of 73 (CI95% 19.88-268.14) for heavy smokers exposed to more than 147 Bq/m3. Less frequent histological 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. Impact: Public health initiatives should address the higher risk of lung cancer for smokers exposed to radon.