title: Rare frequency of gene variation and survival analysis in thymic epithelial tumors.
abstract: OBJECTIVE
  Thymic epithelial tumor (TET) is a rare mediastinal neoplasm and little is known about its genetic variability and prognostic factors. This study investigated the genetic variability and prognostic factors of TET.
  
  
  METHODS
  We sequenced 22 cancer-related hotspot genes in TET tissues and matched normal tissues using Ampliseq Ion Torrent next-generation technology. Overall survival was evaluated using Kaplan-Meier methods and compared with log-rank tests.
  
  
  RESULTS
  A histological analysis of 52 patients with a median age of 52 years showed 15 patients (28.8%) with thymic carcinoma, five with type A thymoma (9.6%), eight with type AB (15.4%), six with type B1 (11.5%), nine with type B2 (17.3%), and nine with type B3 thymoma (17.3%). Three gene mutations were identified, including two withPIK3CAmutation and one withEGFRmutation. The three patients with mutant genes included two cases of thymoma (one withEGFRand the other withPIK3CAmutation) in addition to a case of thymic carcinoma (PIK3CAmutation). The 5-year survival rates were 77.7% in all patients. The 5-year survival rates were 93.3%, 90.0%, 76.9%, and 22.9% corresponding to Masaoka stages I, II, III, and IV (P<0.001). The 5-year survival rates were 100%, 100%, 83.3%, 88.9%, 65.6%, and 60.9% in the histological subtypes of A, AB, B1, B2, and B3 thymomas, and thymic carcinoma, respectively (P=0.012).
  
  
  CONCLUSIONS
  Hotspot gene mutations are rare in TET.PIK3CAandEGFRmutations represent candidate driver genes and treatment targets in TET. Masaoka stage and histological subtypes predict the survival of TET.
authors: Department of Medical Oncology, Zhejiang Cancer Hospital; Key Laboratory Diagnosis and Treatment Technology on Thoracic Oncology, Zhejiang Province, Hangzhou, People's Republic of China.
authors: Zhengbo
authors: Z
authors: Song
authors: Department of Medical Oncology, Zhejiang Cancer Hospital; Key Laboratory Diagnosis and Treatment Technology on Thoracic Oncology, Zhejiang Province, Hangzhou, People's Republic of China.
authors: Xinmin
authors: X
authors: Yu
authors: Department of Medical Oncology, Zhejiang Cancer Hospital; Key Laboratory Diagnosis and Treatment Technology on Thoracic Oncology, Zhejiang Province, Hangzhou, People's Republic of China.
authors: Yiping
authors: Y
authors: Zhang
keywords: gene mutation; prognosis; thymic epithelial tumors