title: Impact of the Ki-67 proliferation index on response to peptide receptor radionuclide therapy.
abstract: OBJECTIVE
  The role of the Ki-67 tumour proliferation index (PI) in predicting the efficacy of peptide receptor radionuclide therapy (PRRT) in gastroenteropancreatic tumours (GEP-NET) remains undetermined. This single-centre analysis focused on the potential therapeutic impact of this immunohistochemical parameter.
  
  
  METHODS
  A total of 81 consecutive GEP-NET patients treated with (177)Lu-DOTA-octreotate (mean activity of 7.9 GBq per cycle, usually four treatment cycles at standard intervals of 3 months) were retrospectively analysed. Both an evaluable PI and tumour response (modified SWOG criteria) were required for patient inclusion.
  
  
  RESULTS
  Response of tumours with a PI of ≤20% (partial response 40%, minor response 15%, stable disease 34%, progressive disease 11%) was comparable in all PI subsets, including those with a PI of 20%. However, G3 tumours (PI > 20%) showed progression in 71% of patients.
  
  
  CONCLUSIONS
  Response to PRRT is consistent over the PI range of ≤20% (G1 + G2). Contrary to preliminary previous suggestions, a PI of 15% or 20% should not preclude candidates from somatostatin receptor-targeted radiotherapy.
authors.affiliation: Department of Nuclear Medicine, University Hospital, Bonn, Germany. samer.ezziddin@ukb.uni-bonn.de
authors.forename: Samer
authors.initials: S
authors.lastname: Ezziddin
authors.forename: Martin
authors.initials: M
authors.lastname: Opitz
authors.forename: Mared
authors.initials: M
authors.lastname: Attassi
authors.forename: Kim
authors.initials: K
authors.lastname: Biermann
authors.forename: Amir
authors.initials: A
authors.lastname: Sabet
authors.forename: Stefan
authors.initials: S
authors.lastname: Guhlke
authors.forename: Holger
authors.initials: H
authors.lastname: Brockmann
authors.forename: Winfried
authors.initials: W
authors.lastname: Willinek
authors.forename: Eva
authors.initials: E
authors.lastname: Wardelmann
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Biersack
authors.forename: Hojjat
authors.initials: H
authors.lastname: Ahmadzadehfar
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D049109:Cell Proliferation; D015331:Cohort Studies; D004067:Digestive System Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D019394:Ki-67 Antigen / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000378:metabolism / Q000473:pathology* / Q000532:radiotherapy*; D018000:Receptors, Peptide / Q000627:therapeutic use*; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D019394:Ki-67 Antigen; D018000:Receptors, Peptide