1. Department of Epidemiology and Biostatistics, National Institute for Health Development, Tallinn, Estonia;
2. Department of Chemotherapy, Clinic of Haematology and Oncology, North Estonia Medical Centre, Tallinn, Estonia;
3. Department of Thoracic Surgery, Lung Clinic, Tartu University Hospital, Tartu, Estonia;
4. Department of Pulmonology, Faculty of Medicine, University of Tartu, Tartu, Estonia