[1] Princess Margaret Canc Ctr, Toronto, ON, Canada
[2] Princess Margaret Canc Ctr, Dept Radiat Oncol, Toronto, ON, Canada
[3] Princess Margaret Canc Ctr, Dept Biostat, Toronto, ON, Canada
[4] Fdn IRCCS Ist Nazl Tumori, Head & Neck Canc Med Oncol Unit, Milan, Italy
[5] Princess Maragaret Canc Ctr, Dept Radiat Oncol, Toronto, ON, Canada
[6] Princess Maragaret Canc Ctr, Div Med Oncol, Toronto, ON, Canada
[7] Univ Toronto, Sunnybrook Odette Canc Ctr, Toronto, ON, Canada
[8] Princess Margaret Canc Ctr, Lab Med Program, Toronto, ON, Canada
[9] Fdn IRCCS Ist Nazl Tumori, Head & Neck Canc Med Oncol Unit, Milan, Italy
[10] Fdn IRCCS Ist Nazl Tumori, Unit Radiotherapy2, Milan, Italy
[11] Fdn IRCCS Ist Nazl Tumori, Milan, Italy