title: Clinicopathological analysis of thymic malignancies with a consistent retrospective database in a single institution: from Tokyo Metropolitan Cancer Center.
abstract: BACKGROUND
  Thymic epithelial tumors (TETs), which comprise thymoma and thymic carcinoma, are rare cancers with specific morphological and clinical features. Their clinical characteristics and outcomes have gradually been clarified by assessing large-scale, retrospective data obtained with international cooperation.
  
  
  METHODS
  The study is a retrospective review of 187 Japanese patients with TETs who attended our institution from 1976 to 2012. Relevant clinical features of patients with TETs and their tumors, including histology, staging, treatment strategies, and overall survival, were investigated. Differences in survival were assessed by the Kaplan-Meier method and uni- and multi-variate Cox proportional hazards regression analyses.
  
  
  RESULTS
  The 187 patients included 52 patients with stage I, 37 with stage II, 22 with stage III, and 76 with stage IVa/IVb tumors according to the Masaoka-Koga Staging System. As to histological type, five patients had type A, 33 type AB, 19 type B1, 39 type B2, and 15 type B3 thymomas, whereas 68 patients had thymic carcinoma, including 11 with neuroendocrine carcinomas according to the 2004 WHO classification. Either insufficient data were available to classify the tumors of the remaining eight patients or they had rare types. Immunological abnormalities were present in 26 patients, most of whom had thymomas (21.8% of the thymoma group). Most of the patients who presented with symptoms had myasthenia gravis or extensive thymic carcinoma. Secondary cancers were present in 25 patients (13.3%). The overall 5- and 10-year survival rates for thymoma were 85.4 and 71.5%, respectively, and those for thymic carcinoma were 33.8 and 2.3%, respectively. OS differed significantly between stage IVa thymomas and thymic carcinomas. The stage and whether the tumors were thymomas or thymic carcinomas were significant determinants of survival according to multivariate analysis.
  
  
  CONCLUSIONS
  The efficacy of treatments for thymoma and thymic carcinoma should be investigated separately because these tumors differ in their clinical features and prognosis.
authors.affiliation: Department of Thoracic Oncology and Respiratory Medicine, Tokyo Metropolitan Cancer and Infectious diseases Center Komagome Hospital, 3-18-22 Honkomagome, Bunkyo, Tokyo 113-8677, Japan. y-okuma@cick.jp.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Okuma
authors.forename: Yukio
authors.initials: Y
authors.lastname: Hosomi
authors.forename: Kageaki
authors.initials: K
authors.lastname: Watanabe
authors.forename: Yuko
authors.initials: Y
authors.lastname: Yamada
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Horio
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Maeda
authors.forename: Tatsuru
authors.initials: T
authors.lastname: Okamura
authors.forename: Tsunekazu
authors.initials: T
authors.lastname: Hishima
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D005260:Female; D006801:Humans; D007564:Japan; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009367:Neoplasm Staging; D009375:Neoplasms, Glandular and Epithelial / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate; D013945:Thymoma / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D013953:Thymus Neoplasms / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult