1. Department of Radiation Oncology, Namazi Hospital, Shiraz University of Medical Sciences, Shiraz, Iran.
2. Department of Radiation Oncology, Shiraz University of Medical Sciences, Shiraz, Iran.
3. Colorectal Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.
4. Department of Epidemiology, Kerman University of Medical Sciences, Kerman, Iran.
5. Shiraz Institute for Cancer Research, Shiraz University of Medical Sciences, Shiraz, Iran.
6. Department of Biostatistics, Shiraz University of Medical Sciences, Shiraz, Iran.