1. Department of Medical Epidemiology and Biostatistics; Karolinska Institutet; Stockholm 17177 Sweden
2. Division of Cancer Epidemiology and Genetics; National Cancer Institute; 9609 Medical Center Drive Rockville Maryland
3. Genomics Research Center; Academia Sinica; Taipei Taiwan
4. Department of Otolaryngology; National Taiwan University Hospital and National Taiwan University College of Medicine; Taipei Taiwan
5. Westat; 1600 Research Blvd Rockville Maryland
6. Graduate Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University; Taipei Taiwan