title: Establishment of an innovative staging system for extramedullary plasmacytoma.
abstract: Extramedullary plasmacytoma (EMP) is a rare malignant disease that lacks a unique clinical staging system to predict the survival of EMP patients and to design individualized treatment. Instead, clinicians have chosen to use the multiple myeloma (MM) staging system.
  
  
  
  Forty-eight EMP patients treated between 1996 and 2014 were included in this study. The new clinical stages were established according to independent survival factors using Cox regression model.
  
  
  
  Lymph node metastasis and a larger primary tumor (≥5 cm) were the only two independent poor prognostic factors for overall survival (OS) and disease-free survival (P < 0.05). Stage I was defined as the disease without those two poor prognostic factors. Stage II was defined as the presence of either factor, and Stage III was defined as the presence of both factors. OS was significantly different in each stage of the new staging system (P < 0.001), with a median follow-up time for Stage I, Stage II and Stage III of 68, 23 and 14 months. The new staging system had enhanced prognostic value compared to the MM staging system (the area under ROC 0.763 versus 0.520, P = 0.044). Although no difference was observed between treatments in Stage I, the combination treatment was associated with a significantly beneficial OS in the late stages (5-year OS: 15.3 % versus 79.5 %; P = 0.032).
  
  
  
  The new staging system exhibited a promising prognostic value for survival and could aid clinicians in choosing the most suitable treatment for EMP patients.
authors.affiliation: Department of Nasopharyngeal Carcinoma, State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhu
authors.affiliation: Department of Nasopharyngeal Carcinoma, State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong, China.
authors.forename: Xiong
authors.initials: X
authors.lastname: Zou
authors.affiliation: Department of Nasopharyngeal Carcinoma, State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong, China.
authors.forename: Rui
authors.initials: R
authors.lastname: You
authors.affiliation: Department of Nasopharyngeal Carcinoma, State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong, China.
authors.forename: Rou
authors.initials: R
authors.lastname: Jiang
authors.affiliation: Department of Nasopharyngeal Carcinoma, State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong, China.
authors.forename: Meng-Xia
authors.initials: MX
authors.lastname: Zhang
authors.affiliation: Department of Nasopharyngeal Carcinoma, State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong, China.
authors.forename: You-Ping
authors.initials: YP
authors.lastname: Liu
authors.affiliation: Department of Nasopharyngeal Carcinoma, State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong, China.
authors.forename: Chao-Nan
authors.initials: CN
authors.lastname: Qian
authors.affiliation: Department of Nasopharyngeal Carcinoma, State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong, China.
authors.forename: Hai-Qiang
authors.initials: HQ
authors.lastname: Mai
authors.affiliation: Department of Nasopharyngeal Carcinoma, State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong, China.
authors.forename: Ming-Huang
authors.initials: MH
authors.lastname: Hong
authors.affiliation: Department of Nasopharyngeal Carcinoma, State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong, China. guol201566@163.com.|Department of Nasopharyngeal Carcinoma, Sun Yat-Sen University Cancer Center, 651 Dongfeng Dong Road, Guangzhou, 510060, Guangdong, China. guol201566@163.com.
authors.forename: Ling
authors.initials: L
authors.lastname: Guo
authors.affiliation: Department of Nasopharyngeal Carcinoma, State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong, China. chmingy@mail.sysu.edu.cn.|Department of Nasopharyngeal Carcinoma, Sun Yat-Sen University Cancer Center, 651 Dongfeng Dong Road, Guangzhou, 510060, Guangdong, China. chmingy@mail.sysu.edu.cn.
authors.forename: Ming-Yuan
authors.identifier: 0000-0003-4657-2787
authors.initials: MY
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D010954:Plasmacytoma / Q000473:pathology* / Q000628:therapy*; D011379:Prognosis; D016019:Survival Analysis; D047368:Tumor Burden; D055815:Young Adult
keywords: Clinical stage; Extramedullary plasmacytoma; Prognostic factors