Multimodal treatment of children with sacrococcygeal yolk sac tumor: retrospective analysis of clinicopathology characteristics and relapse-free survivalJia Zhu,1∗Huadong Chen,2∗ Tingting Chen,1∗Zijun Zhen,1* Juan Wang,1 Feifei Sun,1 Suying Lu,1 Junting Huang,1 Yizhuo Zhang,1 Xiaofei Sun1△1 Department of Pediatric Oncology, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, 510060, P.R.China2 Department of Pediatric Surgery, The First Affiliated Hospital of Sun Yat-Sen University, Zhongshan Er Lu, Guangzhou, 510080, P.R.China.Running title: Relapse-free survival of sacrococcygeal yolk sac tumor△Corresponding author: Xiaofei Sun MD, Department of Pediatric Oncology, Sun Yat-sen University Cancer Center, 651 Dongfengdong Road, Guangzhou, China, 510060; Tel: +86-20-87342468; Fax: +86-20-87342468; Email:sunxf@sysucc.org.cn∗Jia Zhu, Huadong Chen and Tingting Chen contributed equally to the article.List of Abbreviations