1. Department of Radiation Oncology, Stanford University, Stanford, California
2. Perelman School of Medicine, Department of Radiation Oncology, University of Pennsylvania, Philadelphia
3. Perelman School of Medicine, Department of Biostatistics, Epidemiology and Informatics, University of Pennsylvania, Philadelphia
4. Perelman School of Medicine, Department of Medicine, University of Pennsylvania, Philadelphia
5. Perelman School of Medicine, Department of Medical Ethics and Health Policy, University of Pennsylvania, Philadelphia
6. Corporal Michael J. Crescenz VA Medical Center, Philadelphia, Pennsylvania