title: Comparison of the clinical features and hematopoietic stem cell transplantation outcomes of mediastinal malignant germ cell tumors with nonmediastinal extragonadal placements.
abstract: OBJECTIVE
  Even though the primary mediastinal extragonadal germ cell tumors (EGCTs) are rare, they are noteworthy in the differential diagnosis of mediastinal masses. In this study, we aimed to identify the clinical features of mediastinal malignant GCTs and compare the results of hematopoietic stem cell transplantation between mediastinal and nonmediastinal malignant EGCTs.
  
  
  METHODS
  Data of the patients with EGCT who were treated and underwent hematopoietic stem cell transplantation at our hospital between 1988 and 2015 were retrieved retrospectively. Results were compared between mediastinal and nonmediastinal EGCTs.
  
  
  RESULTS
  Data of 65 patients diagnosed with EGCT (37 [56.92%] cases with mediastinal EGCT and 28 [43.07%] cases with nonmediastinal EGCT) were assessed. The clinical stages, frequency of pretransplant status, mean pretransplant time, and mean number of chemotherapy lines before hematopoietic stem cell transplantation were not significantly different between groups. Although the overall survival did not significantly differ between groups, the 5-year survival was significantly higher in mediastinal EGCTs (P=0.02). Yolk sac tumor was significantly more common in mediastinal EGCTs (P=0.05). Mortality rates were higher in seminomas and yolk sac tumors in all cases, higher in embryonal carcinomas in mediastinal EGCT group and higher in yolk sac tumors in nonmediastinal EGCT group. While choriocarcinomas had more aggressive courses in mediastinal EGCTs, seminomas and yolk sac tumors had poorer prognosis in nonmediastinal EGCTs. Short pretransplant time and persistence of elevated posttransplant βhCG and AFP levels were the significant mortality risk factors both in mediastinal and nonmediastinal EGCTs.
  
  
  CONCLUSIONS
  Mediastinal placement of EGCT was not a poor prognostic factor; furthermore, the 5-year survival was significantly higher in mediastinal EGCTs. According to our knowledge, this is the first study that compares the clinical outcomes of hematopoietic stem cell transplantation of mediastinal and nonmediastinal malignant EGCTs.
authors.affiliation: Department of Chest Diseases.
authors.forename: Nesrin
authors.initials: N
authors.lastname: Ocal
authors.affiliation: Department of Oncology, Gulhane Military Medical Faculty, Ankara, Turkey.
authors.forename: Birol
authors.initials: B
authors.lastname: Yildiz
authors.affiliation: Department of Oncology, Gulhane Military Medical Faculty, Ankara, Turkey.
authors.forename: Nuri
authors.initials: N
authors.lastname: Karadurmus
authors.affiliation: Department of Chest Diseases.
authors.forename: Deniz
authors.initials: D
authors.lastname: Dogan
authors.affiliation: Department of Oncology, Gulhane Military Medical Faculty, Ankara, Turkey.
authors.forename: Sukru
authors.initials: S
authors.lastname: Ozaydin
authors.affiliation: Department of Hematology, Medical Faculty, Gazi University, Ankara, Turkey.
authors.forename: Ramazan
authors.initials: R
authors.lastname: Ocal
authors.affiliation: Department of Oncology, Gulhane Military Medical Faculty, Ankara, Turkey.
authors.forename: Mustafa
authors.initials: M
authors.lastname: Ozturk
authors.affiliation: Department of Oncology, Liv Hospital, Ankara, Turkey.
authors.forename: Fikret
authors.initials: F
authors.lastname: Arpaci
authors.affiliation: Department of Chest Diseases.
authors.forename: Hayati
authors.initials: H
authors.lastname: Bilgic
keywords: extragonadal germ cell tumor; hematopoietic stem cell transplantation; mediastinum; survival; tumor marker; α-fetoprotein; βhCG