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
2640 - Health-related quality of life issues of patients affected by desmoid-type fibromatosis; experiences from two countries
Presenter: Milea Timbergen
Session: Poster Display session 1
Resources:
Abstract
1269 - One-year follow-up results of eribulin for soft-tissue sarcoma including rare subtypes in a real-world observational study in Japan
Presenter: Shunji Takahashi
Session: Poster Display session 1
Resources:
Abstract
2868 - Prevalence of chemotherapy use and its impact on overall survival in patients with bone- and soft tissue sarcomas -A population-based analysis of 3746 patients
Presenter: Herbert Loong
Session: Poster Display session 1
Resources:
Abstract
3042 - Clinical course and therapeutic management of classical and endemic Kaposi’s Sarcoma (C/E KS)
Presenter: Lina Benajiba
Session: Poster Display session 1
Resources:
Abstract
3141 - The final outcomes of study on combined therapy of adult patients with localized synovial sarcoma
Presenter: Katarzyna Kozak
Session: Poster Display session 1
Resources:
Abstract
5449 - Real-world Outcomes of Patients with Locally Advanced or Metastatic Epithelioid Sarcoma
Presenter: Mrinal Gounder
Session: Poster Display session 1
Resources:
Abstract
4465 - SAKK 57/16 Nab-Paclitaxel And Gemcitabine in soft tissue sarcoma (NAPAGE): results from the phase I part of a phase I/II trial
Presenter: Antonia Digklia
Session: Poster Display session 1
Resources:
Abstract
5013 - Outcome of 98 patients with epithelioid sarcoma treated in curative intent: a retrospective study from the French Sarcoma Group (GSF-GETO)
Presenter: Maud Pedrono
Session: Poster Display session 1
Resources:
Abstract
5614 - Comparison of filgrastim and pegfilgrastim prophylaxis in sarcoma patients receiving highly myelosuppressive chemotherapy.
Presenter: Paolo Tarantino
Session: Poster Display session 1
Resources:
Abstract
1033 - Access to clinical trials for soft tissue sarcoma patients in Western and Eastern Europe
Presenter: Vasilii Ostafiichuk
Session: Poster Display session 1
Resources:
Abstract