1. From the Department of Radiation Oncology, Dana-Farber Cancer Institute, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA; Departments of Biometry, Radiation Oncology, and Medical Oncology, London Regional Cancer Centre, London; Department of Medical Oncology, Kingston Regional Cancer Centre, Kingston, Ontario; and Department of Radiation Oncology, British Columbia Cancer Agency-Vancouver Island Cancer Centre, Victoria, British Columbia, Canada.