[1] Univ Laval, Clin Epidemiol Unit, Canc Res Ctr, CHUQ Hotel Dieu Quebec, Quebec City, PQ G1R 2J6, Canada
[2] Quebec Univ Hosp, Dept Radiooncol, Quebec City, PQ, Canada
[3] Montreal Univ Hosp, Dept Radiooncol, Quebec City, PQ, Canada
[4] Sherbrooke Univ Hosp, Dept Radiooncol, Montreal, PQ, Canada
[5] Sagamie Hosp, Dept Radiooncol, Saguenay, PQ, Canada
[6] Univ Laval, Quebec Univ Hosp, Dept Pathol, Quebec City, PQ, Canada