1. Institute of Cancer Prevention and Treatment, Harbin Medical University, Harbin, China
2. Institute of Cancer Prevention and Treatment, Heilongjiang Province Academy of Medical Sciences, Harbin, China
3. Department of Epidemiology and Biostatistics, College of Human Medicine, Michigan State University, East Lansing, MI, USA
4. Institute of Advanced Technology, Heilongjiang Academy of Sciences, Harbin, China
5. Department of Radiation Oncology, Harbin Medical University Cancer Hospital, Harbin Medical University, Harbin, China