e-Poster Presentation Clinical Oncology Society of Australia Annual Scientific Meeting 2020

Metabolic Tumour Volume (MTV) on 18-Fluorodeoxyglucose Positron Emission Tomography (FDGPET) as a prognostic marker of survival in patients with Metastatic Neuroendocrine Neoplasms (mNENs) receiving 177Lutetium-DOTA-octreotate (Lutate). (#221)

Madhawa De Silva 1 , David Chan 1 , Elizabeth Bernard 2 , Alice Connor 1 , Sophie Mascall 1 , Dale Bailey 2 , Paul Roach 2 , Nick Pavlakis 1 , Geoffrey Schembri 2
  1. Department of Medical Oncology, Royal North Shore Hospital, St Leonards, NSW, Australia
  2. Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW, Australia

INTRODUCTION/AIMS:  Prior work has demonstrated quantitative analysis of FDGPETs in mNENs is feasible. FDG avidity correlates with high-grade disease, and high MTV and total lesion glycolysis (TLG) portend poor prognosis. We aimed to investigate MTV and TLG on baseline FDGPET as prognostic markers for survival in patients with mNENs receiving Lutate.

METHODS: A retrospective review of mNENs undergoing baseline FDGPET and Lutate at Royal North Shore Hospital (December 2010 to November 2019). Images were analysed with automated segmentation (SUV cut-off 4.0) followed by contour verification by a nuclear medicine physician and manual segmentation where required. Variables collected included MTV and TLG (dichotomised by median into high vs low), and SUVmax/SUVmean. Primary outcome was overall survival (OS) by MTV (high vs low). Secondary outcome was progression-free survival (PFS) by MTV (high vs low). Survival data were compared using the log-rank test.

RESULTS: One hundred and five patients were included (median age 64 years, 50% male). Primary sites of mNENs were small bowel (44%), pancreas (40%), and lung (8%).  Median MTV was 3.8 ml (IQR 0 - 58.7) and median TLG was 19.3 (IQR 0 - 310.3). Overall median OS was 72 months; OS was not different based on MTV-high vs MTV-low (47.4 months vs not reached, HR 0.43, CI 0.18-1.04, p = 0.0594). Overall median PFS was 30.4 months; PFS was different based on MTV-high vs MTV-low (21.6 months vs 45.7 months, HR 0.35, CI 0.19-0.64, p = 0.007).    

CONCLUSIONS: Low MTV on baseline FDGPET was associated with a statistically significant PFS benefit in mNEN patients receiving Lutate. Low MTV also showed a trend toward OS benefit, though this was not statistically significant. Quantitative analysis of FDGPET in mNENs is feasible, and may assist in treatment decisions, in particular determining the urgency.