1. Division of Medical Oncology and Hematology, Princess Margaret Cancer Centre, Toronto, ON, Canada
2. Department of Biostatistics, Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada
3. Department of Community Health and Epidemiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
4. Princess Margaret Cancer Registry, Cancer Clinical Research Unit, University Health Network, Toronto, ON, Canada
5. Department of Otolaryngology-Head and Neck Surgery, Surgical Oncology, Princess Margaret Cancer Centre, University of Toronto, Toronto, ON, Canada
6. Department of Radiation Medicine, Princess Margaret Cancer Centre, University of Toronto, Toronto, ON, Canada
7. Department of Medicine, University of Toronto, Toronto, ON, Canada