title: The Impact of Radiological Response to Peptide Receptor Radionuclide Therapy on Overall Survival in Patients With Metastatic Midgut Neuroendocrine Tumors.
abstract: OBJECTIVE
  Peptide receptor radionuclide therapy (PRRT) is an effective treatment for advanced neuroendocrine tumors (NET); however, long-term survival data are scarce. The aim of this study is to determine long-term survival in patients with metastatic midgut NET, according to response to PRRT.
  
  
  METHODS
  One hundred thirty-three consecutive patients with progressive metastatic midgut NET underwent PRRT. Response at 1 year post PRRT was classified as partial response, stable disease, disease progression, or death. Survival was assessed according to response to PRRT, and predictors of overall survival (OS) and progression-free survival (PFS) were identified.
  
  
  RESULTS
  At 1 year post PRRT, 9% had partial response, 50.4% stable disease, 10.5% disease progression, and 30.1% were dead. The OS was 33.5, and PFS was 28.5 months. Predictors of disease progression/death were chromogranin A greater than 10 ULN (OR, 4.6; P = 0.007) and hepatic tumor load greater than 50% (OR, 5; P = 0.004). There was no difference in OS between patients with partial response and those with stable disease post PRRT. In multivariate Cox regression, predictors of OS were number of PRRT cycles (HR, 0.33; P < 0.0005), hepatic tumor load greater than 50% (HR, 3.46; P = 0.01), and outcome at 1 year post PRRT (HR, 21.37; P < 0.0005). Predictors of PFS were number of PRRT cycles (HR, 0.39; P < 0.0005), previous resection of liver metastases (HR, 3.56; P = 0,023), and hepatic tumor load greater than 50% (HR, 3.06; P < 0.0005).
  
  
  CONCLUSIONS
  Patients with progressive metastatic midgut NET who achieved stable disease at 1 year post PRRT had similar OS with those with partial response. Hepatic tumor burden was a strong predictor of response to PRRT, PFS, and OS.
authors.affiliation: From the *Neuroendocrine Tumour Unit, ENETS Centre of Excellence, Royal Free Hospital, London; †Care of the Elderly, University College Hospital, London; ‡Nuclear Medicine Department, Royal Free Hospital, London; and §Faculty of Medicine, St Mary's Campus, Imperial College London, London, UK.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Yalchin
authors.forename: Amelia
authors.initials: A
authors.lastname: Oliveira
authors.forename: Eleni
authors.initials: E
authors.lastname: Theocharidou
authors.forename: Deborah
authors.initials: D
authors.lastname: Pencharz
authors.forename: Shaunak
authors.initials: S
authors.lastname: Navalkissoor
authors.forename: Ann-Marie
authors.initials: AM
authors.lastname: Quigley
authors.forename: Martin
authors.initials: M
authors.lastname: Walker
authors.forename: Martyn
authors.initials: M
authors.lastname: Caplin
authors.forename: Christos
authors.initials: C
authors.lastname: Toumpanakis
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007414:Intestinal Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D015282:Octreotide / Q000031:analogs & derivatives / Q000627:therapeutic use*; D019275:Radiopharmaceuticals / Q000627:therapeutic use*; D016019:Survival Analysis
chemical_list: D019275:Radiopharmaceuticals; D015282:Octreotide