title: The presence of extrathoracic metastasis is more prognostic of survival than Masaoka stage (IVa/IVb) in metastatic thymic epithelial tumor: a retrospective cohort study.
abstract: OBJECTIVE
  Our aim in this study was to identify independent prognostic factors for overall survival (OS) in order to explain the heterogeneity of OS in patients with metastatic thymic epithelial tumor (TET).
  
  
  METHODS
  Sixty-one consecutive patients with histologic diagnosis of Masaoka stage IV TET between January 1980 and March 2009 were analyzed at a single institution. Masaoka stage IVa was defined as pleural or pericardial dissemination, and IVb as lymphogenous or hematogenous metastasis. Metastasis outside the thoracic cage was defined as extrathoracic metastasis. To identify prognostic factors, relationships between clinicopathologic factors and outcomes were analyzed.
  
  
  RESULTS
  Of the 61 patients, 30 (49.2%) had thymoma, 28 (45.9%) had thymic carcinoma, and the remaining 3 (4.9%) had an unclear histologic subtype. The Masaoka stage was IVa in 27 patients (44.3%) and IVb in 34 patients (55.7%). Significant independent adverse prognostic factors for OS were histologic subtype and extrathoracic metastasis (hazard ratio [HR]=3.09 and 6.03, 95% CI: 1.41-6.74 and 1.89-19.30, p=0.005 and 0.002, respectively). The presence of extrathoracic metastasis was also an independent prognostic factor for decreased progression-free survival time (PFS) (HR=6.62, 95% CI: 1.19-24.17, p=0.004). The only significant criterion for prognostic discrimination was the presence of extrathoracic metastasis in metastatic TET.
  
  
  CONCLUSIONS
  Significant independent prognostic factors for lower OS were the histologic subtype of thymic carcinoma and the presence of extrathoracic metastasis. A new concept of extrathoracic metastasis might provide additional information for the understanding of metastatic TET.
authors: Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors: Dong-Yeop
authors: DY
authors: Shin
authors: Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea; Cancer Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea. Electronic address: kimdw@snu.ac.kr.
authors: Dong-Wan
authors: DW
authors: Kim
authors: Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea; Cancer Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors: Bhumsuk
authors: B
authors: Keam
authors: Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea; Cancer Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors: Tae Min
authors: TM
authors: Kim
authors: Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea; Cancer Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors: Se-Hoon
authors: SH
authors: Lee
authors: Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, Seoul, Republic of Korea.
authors: Chang Hyun
authors: CH
authors: Kang
authors: Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, Seoul, Republic of Korea.
authors: Young Tae
authors: YT
authors: Kim
authors: Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea; Cancer Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors: Dae Seog
authors: DS
authors: Heo
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D009375:Neoplasms, Glandular and Epithelial / Q000401:mortality* / Q000473:pathology* / Q000628:therapy; D011379:Prognosis; D012189:Retrospective Studies; D013953:Thymus Neoplasms / Q000401:mortality* / Q000473:pathology* / Q000628:therapy; D055815:Young Adult
keywords: Extrathoracic metastasis; Neoplasm; Overall survival; Prognostic factor, Masaoka stage IV; Thymic epithelial tumor