1. Cancer Prevention and Control, Duke Cancer Institute, Duke University, Durham, North Carolina, USA.
2. Division of General Internal Medicine, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA.
3. Division of General Internal Medicine, Section of Palliative Care and Medical Ethics, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
4. Department of Population Health Sciences, Duke University School of Medicine, Durham, North Carolina, USA.
5. Department of Biology, Geology, and Environmental Science, University of Tennessee at Chattanooga, Chattanooga, Tennessee, USA.