Margriet Kwint

Chapter 3 52 Hence, radical local treatment on the primary tumor and the metastases seems to improve survival in oligometastatic NSCLC disease [7,8,11,13-15,18-20]. Since a radical treatment approach for synchronous oligometastatic NSCLC is not standard of care according to current treatment guidelines, more evidence is needed to confirm the benefit of this therapeutic approach. Therefore, the purpose of this observational study was to determine the progression free survival (PFS) and overall survival (OS) of NSCLC patients with good performance, diagnosed with synchronous oligometastatic (<5 metastases) disease treated with curative intent of the intrathoracic disease and the metastases. Materials and methods Patients diagnosed with synchronous oligometastatic NSCLC who were treated between July 2008 and August 2016 were included in this observational study. Patients were selected during the multidisciplinary tumor board meeting for thoracic cancer in our institute. When radical local treatment for oligometastatic disease was considered, patients were registered in a database between 2008 and 2016. Details of all patients were retrospectively retrieved using this registration database, with subsequent review of all the patients’ charts. Patients who had progressive disease before they finished their radical local treatment were not registered in the database. The Institutional Review Board of our institute waived review because of the retrospective nature of the study. Inclusion criteria for this analysis included histological or cytological proven NSCLC and less than 5 synchronous metastases at the time of diagnosis. Patients were excluded if they had other uncontrolled malignancies. Staging was done for all patients by fluorodeoxyglucose-positron-emission-tomography-(FDG-PET)-scan, CT-thorax and for the brain a contrast-enhanced magnetic resonance imaging (CE-MRI) or a CT of the brain with intravenous contrast. Ideally, metastatic disease was pathologically proven but this was not mandatory. Different types of local therapies were allowed. Systemic therapy was not mandatory. For the primary tumor, treatment was considered radical if the patient underwent surgery or if a radical radiotherapy dose was given (≥55 Gy biological equivalent dose (EQD2) / α/ß=10). For the treatment of the metastases, sometimes a lower radiation dose was prescribed (stereotactic radiation for brain metastasis: 1x15 up to 1x24 Gy