title: Role of 18FDG PET/CT in patients treated with 177Lu-DOTATATE for advanced differentiated neuroendocrine tumours.
abstract: OBJECTIVE
  The prognostic value of FDG PET for neuroendocrine tumours (NETs) has been reported. In this study we evaluated the role of FDG PET in predicting response and progression-free survival (PFS) after (177)Lu-DOTATATE peptide receptor radionuclide therapy (Lu-PRRT) in patients with advanced well-differentiated grade 1/2 NETs.
  
  
  METHODS
  We retrospectively evaluated 52 patients with progressive advanced NETs overexpressing somatostatin receptors and treated with Lu-PRRT with a cumulative activity up to 27.7 GBq divided into five courses. According to WHO 2010/ENETS classification, patients were stratified into two groups: those with grade 1 tumour (Ki-67 index ≤2 %, 19 patients), and those with grade 2 tumour (Ki-67 index >3 % to <20 %, 33 patients). On the basis of the FDG PET scan, 33 patients were classified as PET-positive (PET+) and 19 as PET-negative (PET-).
  
  
  RESULTS
  FDG PET was positive in 57 % of patients with grade 1 NET and in 66 % of patients with grade 2 NET, and the rates of disease control (DC, i.e. complete response + partial response + stable disease) in grade 1 and grade 2 patients were 95 % and 79 %, respectively (P = 0.232). In PET- and PET+ patients, the DC rates were 100 % and 76 % (P = 0.020) with a PFS of 32 and 20 months, respectively (P = 0.033). Of the PET+ patients with grade 1 NET, 91 % showed disease control, whereas about one in three PET+ patients with grade 2 NET (32 %) progressed after Lu-PRRT (DC rate 68 %).
  
  
  CONCLUSIONS
  These results suggest that FDG PET evaluation is useful for predicting response to Lu-PRRT in patients with grade 1/2 advanced NETs. Notably, none of PET- patients had progressed at the first follow-up examination after Lu-PRRT. Grade 2 NET and PET+ (arbitrary SUV cutoff >2.5) were frequently associated with more aggressive disease. PET+ patients with grade 2 NET, 32 % of whom did not respond to Lu-PRRT monotherapy, might benefit from more intensive therapy protocols, such as the combination of chemotherapy and PRRT.
authors: Unit of Radiometabolic Medicine, Cancer Institute of Romagna (IRST), Meldola, FC, Italy.
authors: Stefano
authors: S
authors: Severi
authors: Oriana
authors: O
authors: Nanni
authors: Lisa
authors: L
authors: Bodei
authors: Maddalena
authors: M
authors: Sansovini
authors: Annarita
authors: A
authors: Ianniello
authors: Stefania
authors: S
authors: Nicoletti
authors: Emanuela
authors: E
authors: Scarpi
authors: Federica
authors: F
authors: Matteucci
authors: Laura
authors: L
authors: Gilardi
authors: Giovanni
authors: G
authors: Paganelli
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018450:Disease Progression; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D019394:Ki-67 Antigen / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging* / Q000628:therapy*; D015282:Octreotide / Q000031:analogs & derivatives* / Q000627:therapeutic use; D009942:Organometallic Compounds / Q000627:therapeutic use*; D011379:Prognosis; D011868:Radioisotopes / Q000627:therapeutic use; D011877:Radionuclide Imaging; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D019394:Ki-67 Antigen; D009942:Organometallic Compounds; D011868:Radioisotopes; C447941:lutetium Lu 177 dotatate; D015282:Octreotide