ESTRO 2024 - Abstract Book

S2067

Clinical - Paediatric

ESTRO 2024

1 University Hospital of Zurich, Radiation Oncology, Zurich, Switzerland. 2 University of Zurich, Faculty of Medicine, Zurich, Switzerland. 3 University Hospital of Zurich, Nuclear Medicine, Zurich, Switzerland. 4 University Hospital Munich, Radiation Oncology, Munich, Germany. 5 Brigham and Women's Hospital, Radiation Oncology, Boston, USA. 6 University Hospital of Zurich, Neurology, Zurich, Switzerland. 7 University Hospital of Zurich, Neurosurgery, Zurich, Switzerland

Purpose/Objective:

There is growing evidence that a sub-group of patients with oligometastatic disease (OMD), defined by a limited tumor burden, might achieve long-term disease-free survival via the integration of definitive local therapy to all active cancer lesions into a multimodality treatment strategy [1–6]. Simultaneously, the diagnosis of brain metastases is a well-established negative prognostic factor for survival, despite recent progress in their local and systemic treatment. This study therefore explores how brain metastases may affect the classification, treatment, and outcomes in oligometastatic cancer patients.

Material/Methods:

A total of 7,000 oncological FDG-PET and PSMA-PET scans were screened to identify cancer patients with extracranial OMD state, leveraging the definition of maximum five extra-cranial metastases [7]. Where available, concurrently acquired brain magnetic resonance imaging scans were assessed to additionally quantify intracranial tumor burden of these patients. Subsequently, the association of brain metastases with the patients’ OMD state, which was now taken to comprise maximum five intra- and extra-cranial metastases, was assessed. Furthermore, we evaluated the association of the presence of brain metastases with selected patient and tumor characteristics, the chosen treatment regimens for intracranial and extracranial metastases, and patient outcomes. For the purposes of our analysis, the patient cohort was stratified into two sub-groups – those that remained oligometastatic after brain scan review, and those that transitioned to a polymetastatic disease state. Predictors for transitioning from an extracranial oligometastatic to a polymetastatic disease state after accounting for intracranial tumor burden were analyzed by regression analysis.

Results: