1. Department of Palliative Care and Rehabilitation, University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA
2. Department of Biostatistics, University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA
3. E Bruera (corresponding author) Department of Palliative Care and Rehabilitation, Medicine Unit 1414, 1515 Holcombe Boulevard, Houston, Texas, USA 77030;