title: Biological characteristics and treatment outcomes of metastatic or recurrent neuroendocrine tumors: tumor grade and metastatic site are important for treatment strategy.
abstract: BACKGROUND
  Studies about the biology, treatment pattern, and treatment outcome of metastatic/recurrent neuroendocrine tumor (NET) have been few.
  
  
  METHODS
  We enrolled patients with metastatic/recurrent NET diagnosed between January 1996 and July 2007 and retrospectively analyzed.
  
  
  RESULTS
  A total of 103 patients were evaluated. Twenty-six patients (25.2%) had pancreatic NET, 27 (26.2%) had gastrointestinal NET, 2 (1.9%) had lung NET, 28 (27.2%) had NET from other sites, and 20 (19.4%) had NET from unknown origin. The liver was the most common metastatic site (68.9%). Thirty-four patients had grade 1 disease, 1 (1.0%) had grade 2 disease, 15 (14.6%) had grade 3 disease, 9 (8.7%) had large cell disease, and 7 (6.8%) had small cell disease.Sixty-six patients received systemic treatment (interferon, somatostatin analogues or chemotherapy), 64 patients received local treatment (TACE, radiofrequency ablation, metastasectomy, etc.). Thirty-six patients received both systemic and local treatments.Median overall survival (OS) was 29.0 months (95% confidence interval, 25.0-33.0) in the 103 patients. OS was significantly influenced by grade (p = .001). OS was 43.0, 23.0, and 29.0 months in patients who received local treatment only, systemic treatment only, and both treatments, respectively (p = .245). The median time-to-progression (TTP) was 6.0 months. Overall response rate was 34.0% and disease-control rate was 64.2%. TTP was influenced by the presence of liver metastasis (p = .011).
  
  
  CONCLUSIONS
  OS of metastatic/recurrent NET was different according to tumor grade. TTP was different according to metastasis site. Therefore, development of optimal treatment strategy based on the characteristics of NET is warranted.
authors: Department of Internal Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors: Su-Jung
authors: SJ
authors: Kim
authors: Jin Won
authors: JW
authors: Kim
authors: Sae-Won
authors: SW
authors: Han
authors: Do-Youn
authors: DY
authors: Oh
authors: Se-Hoon
authors: SH
authors: Lee
authors: Dong-Wan
authors: DW
authors: Kim
authors: Seock-Ah
authors: SA
authors: Im
authors: Tae-You
authors: TY
authors: Kim
authors: Dae
authors: D
authors: Seog Heo
authors: Yung-Jue
authors: YJ
authors: Bang
mesh_terms: D000328:Adult; D000368:Aged; D001859:Bone Neoplasms / Q000556:secondary* / Q000628:therapy; D001932:Brain Neoplasms / Q000556:secondary* / Q000628:therapy; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000556:secondary* / Q000628:therapy; D008175:Lung Neoplasms / Q000556:secondary* / Q000628:therapy; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology* / Q000628:therapy; D018358:Neuroendocrine Tumors / Q000473:pathology* / Q000628:therapy; D012189:Retrospective Studies; D015996:Survival Rate; D016896:Treatment Outcome; D055815:Young Adult