Quality assurance plan: every participant is enrolled or excluded by two practiced investigators. And two investigators participated in all steps of the trail, including the record of the data, and the investigators will compare the data. If the data is consistent, the investigators would record the data; if not, the data would be checked and decided by the two investigators. All the steps and data are site monitored and audited by the workers of research and financial department of National Cancer Center/ Cancer Hospital, Chinese Academy of Medical Sciences.