1 Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.
2 State Key Laboratory of Oncology in South China, Department of Radiation Oncology, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China.
3 Department of Medical Oncology, Antwerp University Hospital, Edegem, Belgium.
4 Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium.
5 Department of Radiation Oncology, Princess Margaret Cancer Center, University of Toronto, Toronto, ON, Canada.