[1] Norwegian Radium Hosp, Palliat Care Res Unit, NO-0310 Oslo, Norway
[2] St Olavs Univ Hosp, Dept Otorhinolaryngol Head & Neck Surg, Trondheim, Norway
[3] Lund Univ, Malmo Univ Hosp, Dept Otorhinolaryngol Head & Neck Surg, Malmo, Sweden
[4] Univ Oslo, Rikshosp, Dept Otorhinolaryngol Head & Neck Surg, N-0027 Oslo, Norway
[5] Gothenburg Univ, Sahlgrenska Univ Hosp, Dept Otorhinolaryngol Head & Neck Surg, Gothenburg, Sweden
[6] Norwegian Radium Hosp, Dept Radiat Oncol, NO-0310 Oslo, Norway