1. 1Department of Radiation Oncology, University of California Los Angeles, Los Angeles, California.
2. 2Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania.
3. 3University of South Carolina, School of Medicine Greenville, Greenville, South Carolina.
4. 4Drexel University School of Medicine, Philadelphia, Pennsylvania.
5. 5Department of Medicine Statistics Core, University of California Los Angeles, Los Angeles, California.