Oral Presentation Asia Pacific Neuroendocrine Tumour Society 2018

The prognostic impact of dual FDG/somatostatin receptor PET in metastatic neuroendocrine tumours: updated overall survival from the NETPET study (#8)

David L Chan 1 2 3 , Paul J Roach 1 , Geoff P Schembri 1 , Elizabeth J Bernard 1 , Edward Hsiao 1 , Aimee R Hayes 1 , Mustafa Khasraw 1 , Jas Samra 1 , Nick Pavlakis 1 2 4 , Dale L Bailey 1 2 5
  1. Royal North Shore hospital, St Leonards, NSW, Australia
  2. Sydney Vital Translational Cancer Research Centre, St Leonards, NSW, Australia
  3. Northern Clinical School, Faculty of Medicine, University of Sydney, St Leonards, NSW, Australia
  4. Medicine, Northern Clinical School, University of Sydney, St Leonards, NSW, Australia
  5. Faculty of Health Sciences, University of Sydney, Camperdown, NSW, Australia

Aims: [F-18]-FDG and [Ga-68]-DOTATATE PET scans are increasingly used in NETs. FDG avidity is associated with high-grade disease and poor prognosis, and DOTATATE avidity is associated with low-grade disease and improved prognosis. However, there is no consensus regarding interpretation of dual PET imaging. We have previously presented a novel proposal for scoring dual FDG/DOTATATE PET (the NETPET score) in metastatic NET (Chan Theranostics 2017). Here we present the updated overall survival findings from the retrospective study.

Methods: Retrospective study of patients with metastatic NET who underwent both FDG and DOTATATE PET/CT within 31 days of each other. The NETPET score was developed as follows: P1 – DOTA+FDG- disease only, P2-P4 – both DOTA+ and FDG+ disease, P5 – significant FDG+DOTA- disease. The score was applied to paired scans by two experienced nuclear medicine physicians. We assessed correlation between NETPET score and histological grade. Potential predictors of overall survival (age, grade, extrahepatic disease, NETPET score) were assessed by univariate and multivariate analysis.

Results: 62 patients (median age 60 years, 35% female; 17 Grade 1, 26 Grade 2, 15 Grade 3) were eligible for inclusion. NETPET score was correlated with histological grade (Chi-squared test, p=0.0001). At the time of analysis, 35/62 patients were still alive (median follow-up 50 months). Median overall survival was as follows: P1 – not reached, P2-4 – not reached (projected 48 months), P5 – 11 months. On univariate analysis, age (p=0.014) and NETPET score (p=0.0011) were significantly associated with overall survival but histological grade (p=0.321) and extrahepatic disease (p=0.068) were not. On multivariate analysis, NETPET score alone (p<0.001) was associated with overall survival.

Conclusions: NETPET score is correlated with histological grade and also overall survival (independent of histological grade). Dual FDG/DOTATATE PET is a promising tool for “whole body molecular biopsy” of NET and should be tested prospectively.

  1. Chan DL, Pavlakis N, Schembri GP, Bernard EJ, Hsiao E, Hayes A et al. Dual Somatostatin Receptor/FDG PET/CT Imaging in Metastatic Neuroendocrine Tumours: Proposal for a Novel Grading Scheme with Prognostic Significance. Theranostics 2017 Mar 1;7(5):1149-1158.