Are outcomes of patients with advanced well-differentiated GEP-NETs on somatostatin analogues similar, irrespective of tracer uptake on 68gallium DOTA SSTR peptide PET CT scans?

Dinakshi Shah, Oliver Loveland, Amarjot Chander, Tom Westwood, Prakash Manoharan, Was Mansoor, Angela Lamarca, Richard A Hubner, Juan Valle, Mairead Mcnamara

Research output: Contribution to conferenceAbstractpeer-review

Abstract

Background: Neuroendocrine tumours (NETs) are a rare and heterogeneous group of neoplasms that mainly originate from the gastroenteropancreatic tract (GEP-NETs). The vast majority of NETs tend to overexpress somatostatin receptors (SSTRs), which can be targeted by somatostatin analogues (SSAs). 68Gallium DOTA SSTR peptide positron emission tracer computed tomography (68Ga PET-CT) has emerged as superior to other imaging modalities in identifying SSTRs. This study aimed to assess whether patients with GEP- NETs treated with SSAs have similar outcomes irrespective of tracer uptake intensity on 68Ga PET-CT.

Methods: Patient cases undergoing 68Ga PET-CT imaging between November 2015 and September 2020 at The Christie NHS Foundation Trust, with diagnosis of histologically-confirmed advanced GEP-NETs receiving SSAs, were reviewed retrospectively. Kaplan-Meier and Cox regression were utilised to analyse progression free (PFS) and overall survival (OS).

Results: Of 644 patients imaged with 68Ga PET-CT, 132 met inclusion criteria. The median age of patients was 62 years; ECOG performance status 0: 62 (47%), 1: 56 (42%), 2: 13 (10%); primary sites: ileum: 54 (41%), pancreas: 26 (20%), cancer of unknown primary: 20 (15%), Grade (G)1: 63 (47%), G2: 56 (42%), G3: 3 (2%), unknown: 11 (8%); 68Ga PET-CT tracer uptake increased: 124 (94%), no increased tracer uptake: 8 (6%). 66 patients (50%) progressed, and 99 (74%) were alive at analysis. Median PFS on SSAs was 20.82 months (95% confidence interval (CI) 12.2–30.03) for patients with increased tracer uptake (n=63) and 8.26 months (95% CI 4.55-not available (NA)) for patients with no increased tracer uptake (n=3) (Hazard Ratio (HR): 4.19 (95% CI 1.238–14.28), P=0.022). Median OS from commencement of SSA was: 99.51 months (95% CI 95.96 – NA) for patients with increased tracer uptake and 47.67 months for patients with no increased tracer uptake (95% CI 13.41 – NA) (HR 2.93 (95% CI 1.011–8.49), P=0.048).

Conclusions: 68Ga PET-CT scans are an accurate tool for diagnosis and localisation of NETs. Median PFS and OS appears to be greater in patients receiving SSAs with increased uptake on the 68Ga PET-CT. However, further evaluation in larger cohorts is needed to definitively assess clinical benefit of SSAs in the 68Ga PET-CT negative cohort.
Original languageEnglish
Publication statusPublished - 2020
EventUKINETs annual conference - Virtual
Duration: 30 Nov 20203 Dec 2020

Conference

ConferenceUKINETs annual conference
Period30/11/203/12/20

Keywords

  • Well-differentiated NETs
  • Gallium scan
  • Outcomes

Research Beacons, Institutes and Platforms

  • Manchester Cancer Research Centre

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