1. Department of Otorhinolaryngology - Head and Neck Surgery; University of Helsinki and Helsinki University Hospital; Helsinki Finland
2. Finnish Cancer Registry; Helsinki Finland
3. Department of Public Health; University of Helsinki; Helsinki Finland
4. Faculty of Social Sciences; University of Tampere; Tampere Finland
5. Division of Ear; Nose, and Throat Diseases, Department of Clinical Sciences, Intervention and Technology, Karolinska Institutet, Karolinska University Hospital; Stockholm Sweden