1 Department of Preventive Medicine and Public Health, University of Santiago de Compostela, Spain; CIBER de Epidemiología y Salud Pública, CIBERESP, Spain. Electronic address: alberto.ruano@usc.es.
2 Department of Preventive Medicine and Public Health, University of Santiago de Compostela, Spain; Service of Medical Oncology, University Hospital Complex of Pontevedra, Spain.
3 Service of Neumology, University Hospital Complex of Vigo, Spain.
4 Department of Preventive Medicine and Public Health, University of Santiago de Compostela, Spain; CIBER de Epidemiología y Salud Pública, CIBERESP, Spain; Service of Preventive Medicine, University Hospital Complex of Santiago de Compostela, Spain.