Abstract 2690
Background
GIST in older adults and in children are well-known entities, but this is not the case for AYA patients with GIST. Typically, GIST in children (70% female) rarely show mutations in KIT or platelet-derived growth factor receptor (PDGFR) (<15%), are often Succinate Dehydrogenase (SDH) deficient, are almost always located in the stomach (90%) and have a relatively indolent course of disease. The typical adult GIST (about 50% female) has mutations in KIT (75%) or PDGFR (15%), stomach as main location and an overall 5-years survival of 65% (SEER data). As data on AYA with GIST are very limited, we aimed to study the clinical and genetic characteristics and outcome of this specific group.
Methods
AYA GIST patients (18-40 years at diagnosis) diagnosed between 2009-2019 and registered in the Dutch GIST Registry (DGR) were included. Patients without mutations in KIT/PDGFR/BRAF and SDH deficiency (by immunohistochemistry) were considered quadruple wildtype (WT). Overall survival (OS) was estimated using Kaplan-Meier method. Furthermore, two subgroups were compared: 18-29 years vs. 30-40 years (Chi-square, Fisher’s exact, Mann-Whitney U test).
Results
From 1011 patients in the DGR, 52 AYA patients (5%) were identified: 54% male, median age 35 years. Main primary tumor locations were stomach (46%) and small intestine (46%). Four AYA patients had a known genetic predisposition: 2 Neurofibromatosis 1 (NF1), 1 Carney Triad, 1 KIT exon 11 germline mutation. GIST genetic profiles were reported as KIT mutation 64%, PDGFR mutation 6%, KIT/PDGFR WT 6%, quadruple WT 8%, SDH deficient 6% and NF1 associated 4%. At diagnosis, 42% had high-risk GIST and 13% metastatic disease.
With a median follow-up of 43 months (0-113), median OS for all patients was 8.9 years with a 5-year survival of 85%. No significant differences were found between the two subgroups with regard to gender, location, size, morphology, risk classification and mutation status.
Conclusions
GIST presenting at AYA age is rare. AYA GIST differ from the well-known paediatric GIST, but are also not fully similar to the typical adult GIST. In our series a remarkable high percentage of small intestine GIST and high-risk tumours were observed, 30% non-KIT/PDGFR mutations and a relatively good survival.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The Netherlands Cancer Institute.
Funding
An unrestricted research grant for the Dutch GIST Registry was received from Novartis, Bayer and Pfizer.
Disclosure
I.M.E. Desar: Research grant / Funding (institution): Novartis; Advisory / Consultancy, advisory board: Eisai; Advisory / Consultancy, advisory board: Lilly. R.H.J. Mathijssen: Research grant / Funding (institution), Travel / Accommodation / Expenses: Astellas; Research grant / Funding (institution): Bayer; Research grant / Funding (institution): Boehringer; Research grant / Funding (institution): Cristal Therapeutics; Honoraria (institution), Research grant / Funding (institution): Novartis; Research grant / Funding (institution): Pamgene; Research grant / Funding (institution), Travel / Accommodation / Expenses: Pfizer; Research grant / Funding (institution): Roche; Research grant / Funding (institution): Sanofi; Honoraria (institution): Servier. N. Steeghs: Research grant / Funding (institution): AstraZeneca/MedImmune; Research grant / Funding (institution): Bayer; Research grant / Funding (institution): Bristol-Myers Squibb; Research grant / Funding (institution): Novartis; Research grant / Funding (institution): GlaxoSmithKline; Research grant / Funding (institution): Pfizer; Research grant / Funding (institution): Roche; Research grant / Funding (institution): Genentech/Roche; Research grant / Funding (institution): Boehringer Ingelheim; Research grant / Funding (institution): Blueprint Medicines; Research grant / Funding (institution): AB science; Research grant / Funding (institution): Deciphera; Research grant / Funding (institution): Genentech; Research grant / Funding (institution): Merck Sharp & Dohme; Research grant / Funding (institution): Amgen; Research grant / Funding (institution): Lilly; Research grant / Funding (institution): Incyte; Research grant / Funding (institution): Merus. W.T.A. van der Graaf: Research grant / Funding (institution): Novartis; Advisory / Consultancy: Bayer. All other authors have declared no conflicts of interest.
Resources from the same session
4325 - Multiple synchronous mechanisms may contribute to osimertinib resistance in non-small cell lung cancer (NSCLC) patients: insights of the MATCH-R study
Presenter: Diego Enrico
Session: Poster Display session 1
Resources:
Abstract
2185 - Sequential treatment with afatinib followed by 3rd generation EGFR-TKI – subgroup analysis of the GIDEON trial: a prospective non-interventional study (NIS) in EGFR mutated NSCLC patients in Germany
Presenter: Wolfgang Brückl
Session: Poster Display session 1
Resources:
Abstract
1524 - Effectiveness of sequencing TKIs in patients with EGFR mutation-positive Non-small-Cell Lung Cancer (NSCLC): A French National medico administrative claim database analysis
Presenter: Nicolas Girard
Session: Poster Display session 1
Resources:
Abstract
5733 - Phase II study of osimertinib in NSCLC patients with EGFR exon 20 insertion mutation: A multicenter trial of the Korean Cancer Study Group (LU17-19)
Presenter: Tae Min Kim
Session: Poster Display session 1
Resources:
Abstract
5440 - Different stories for different EGFR exon 19 deletion variants
Presenter: Chao Zhao
Session: Poster Display session 1
Resources:
Abstract
2982 - Safety and activity of alflutinib in patients with advanced EGFR T790M mutation non-small cell lung cancer who progressed after EGFR-TKI therapy
Presenter: Yuan-Kai Shi
Session: Poster Display session 1
Resources:
Abstract
4002 - Afatinib followed by osimertinib in patients with EGFR mutation-positive (EGFRm+) advanced NSCLC: updated data from the GioTag real-world study
Presenter: Maximilian Hochmair
Session: Poster Display session 1
Resources:
Abstract
2941 - Treatment patterns of EGFR mt+ NSCLC IV pts: Real world data of the NOWEL network
Presenter: Julia Roeper
Session: Poster Display session 1
Resources:
Abstract
4154 - TP53 mutations predicts worse prognosis in EGFR-mutated NSCLC patients receiving TKIs in first- or further line of treatment
Presenter: Matteo Canale
Session: Poster Display session 1
Resources:
Abstract
1175 - HER3 ligand heregulin expression and clinical implication in patients with epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer treated with EGFR-tyrosine kinase inhibitors
Presenter: Kimio Yonesaka
Session: Poster Display session 1
Resources:
Abstract