1. Department of Health Policy and Management, Gillings School of Global Public Health, Chapel Hill, North Carolina, USA
2. Lineberger Comprehensive Cancer Center, Chapel Hill, North Carolina, USA
3. Cecil G. Sheps Center for Health Services Research, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
4. Division of Hematology/Oncology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA