[1] Princess Margaret Hosp, Dept Med, Div Hematol & Med Oncol, Toronto, ON M5G 2M9, Canada
[2] Ontario Canc Inst, Dept Med Biophys, Div Appl Mol Oncol, Toronto, ON M4X 1K9, Canada
[3] McMaster Univ, Community Med Residency Program, Hamilton, ON, Canada
[4] McMaster Univ, Dept Family Med, Hamilton, ON L8S 4L8, Canada
[5] Princess Margaret Hosp, Dept Med, Div Gen Internal Med, Toronto, ON M4X 1K9, Canada
[6] Princess Margaret Hosp, Biostat Unit, Toronto, ON M4X 1K9, Canada
[7] Princess Margaret Hosp, Dept Radiat Oncol, Toronto, ON M4X 1K9, Canada
[8] Univ Toronto, Dept Otolaryngol, Univ Hlth Network, Toronto, ON M5S 1A1, Canada
[9] Univ Laval, Ctr Rech Cancerol, Quebec City, PQ, Canada
[10] Harvard Univ, Massachusetts Gen Hosp, Sch Med, Dept Med, Boston, MA USA
[11] Harvard Univ, Sch Publ Hlth, Dept Environm Hlth, Boston, MA 02115 USA