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
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



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.


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.


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 


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


Novartis, Pfizer and Bayer


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