[1] McMaster Univ, Michael G DeGroote Sch Med, Hamilton, ON, Canada
[2] Inst Canc Res Prevent & Clin Network ISPO, Canc Risk Factors & Lifestyle Epidemiol Unit, Florence, Italy
[3] Netherlands Comprehens Canc Org, Utrecht, Netherlands
[4] Azienda Osped Univ Careggi, Dept Radiat Oncol, Florence, Italy
[5] Univ Toronto, Dept Radiat Oncol, Toronto, ON, Canada
[6] Univ Rochester, Dept Dermatol, Med Ctr, Rochester, NY USA
[7] Univ Rochester, Dept Radiat Oncol, Med Ctr, Rochester, NY USA