[1] Kantonsspital St Gallen, Dept Otorhinolaryngol Head & Neck Surg, CH-9007 St Gallen, Switzerland
[2] Univ Zurich Hosp, Inst Surg Pathol, Zurich, Switzerland
[3] Kantonsspital St Gallen, Clin Trials Unit, CH-9007 St Gallen, Switzerland
[4] German Canc Res Ctr, Res Program Infect & Canc, Dept Genome Modificat & Carcinogenesis, Heidelberg, Germany
[5] Univ Zurich Hosp, Dept Radiat Oncol, Zurich, Switzerland
[6] Univ Zurich Hosp, Dept Otorhinolaryngol Head & Neck Surg, Zurich, Switzerland