1510P - Early response evaluation by 18F-FDG-PET influences management in gastrointestinal stromal tumor patients treated with neo-adjuvant intent

Date 11 September 2017
Event ESMO 2017 Congress
Session Poster display session
Topics GIST
Imaging, Diagnosis and Staging
Sarcoma
Presenter Sheima Farag
Citation Annals of Oncology (2017) 28 (suppl_5): v521-v538. 10.1093/annonc/mdx387
Authors S. Farag1, L. de Geus-Oei2, W.T.A. van der Graaf3, F. Van Coevorden4, D.J. Grunhagen5, A. Reyners6, P. Boonstra6, I. Desar7, H. Gelderblom8, N. Steeghs1
  • 1Medical Oncology, The Netherlands Cancer Institute Antoni van Leeuwenhoek Hospital, 1066 CX - Amsterdam/NL
  • 2Department Of Radiology, Leiden University Medical Center (LUMC), Leiden/NL
  • 3Sarcoma Unit, The Institute of Cancer Research and the Royal Marsden Hospital , Sutton/GB
  • 4Surgical Oncology, The Netherlands Cancer Institute Antoni van Leeuwenhoek Hospital, 1066 CX - Amsterdam/NL
  • 5Surgical Oncology, Erasmus MC - Cancer Institute, 3015 CE - Rotterdam/NL
  • 6Medical Oncology, University Hospital Groningen (UMCG), 9700 RB - Groningen/NL
  • 7Medical Oncology, Radboud University Medical Centre Nijmegen, 6500 HB - Nijmegen/NL
  • 8Medical Oncology, Leiden University Medical Center (LUMC), Leiden/NL

Abstract

Background

Early response evaluation by 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is effective in gastrointestinal stromal tumors (GISTs) treated with imatinib and recommended in GISTs treated with neo-adjuvant intent. Yet, it is unclear whether this effects treatment decisions.

Methods

All patients in the Dutch GIST Registry treated with imatinib with neo-adjuvant intent were identified. Only FDG-PETs made within 8 weeks after initiation or change (in dose or switch) of imatinib were included. Responses were derived from radiological reports and defined in 3 categories: 1) complete response; 2) partial response; 3) no response. Change in management was defined as a difference between pre-PET and post-PET treatment plans. Four categories were defined: change in 1) surgical management; 2) systemic treatment; 3) treatment objective (from curative to palliative); 4) management regarding a second tumor.

Results

Seventy FDG-PETs for early response evaluation in 63 patients treated with neo-adjuvant intent were identified. Forty-one patients (65.1%) had a KIT exon 11 and 22 (34.9%) had a non-KIT exon 11 mutation (15 other and 7 unknown mutations). Of the 70 scans 64 (87.1%) had a baseline, 50 (71.5%) showed metabolic response (partial and complete), and 18 (25.7%) led to change in management. Change in management was strongly correlated with a lack of response (p 

Conclusions

In contrast to GIST patients harboring a KIT exon 11 mutation, in non-KIT exon 11 mutated GISTs treated with neoadjuvant intent early response evaluation by FDG-PET often leads to change in management.

Clinical trial identification

Legal entity responsible for the study

Neeltje Steeghs

Funding

Novartis, Pfizer and Bayer

Disclosure

N. Steeghs: Research grant for the Dutch GIST Registry from Novartis, Pfizer and Bayer. All other authors have declared no conflicts of interest.