5. Follow-up The follow-up of this study divide into two parts, the postoperative quality of life and tumor characteristics outcomes. The information of the postoperative quality of life is collected by the EuroQol-5 Dimensions (EQ-5D) questionnaire in four postoperative time intervals. The tumor related outcomes included long-term postoperative complications, recurrence type, relapse free survival (months) and the overall survival (months).