1. Pfizer Inc, Groton, Connecticut
2. Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston
3. Division of Cardiovascular Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
4. Department of Health Research and Policy, Stanford University School of Medicine, Palo Alto, California
5. Department of Gastrointestinal Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston
6. Department of Biostatistics, Harvard University, Boston, Massachusetts