Immunotherapy, Chemotherapy, Radiotherapy and Surgery for Synchronous Oligo-metastatic NSCLC

Inclusion Criteria: * Histologically confirmed non-small cell lung cancer * Synchronous oligo-metastatic stage IV disease: maximum of three distant metastases, one of which must be extra-cerebral for stereotactic body radiotherapy (SBRT); Initial mediastinal staging is recommended (except for lymph nodes \<1 cm on CT and PET-negative) preferentially by endobronchial ultrasound (EBUS); Neurosurgical resection of one single central nervous system (CNS) metastasis or laparoscopic resection of one adrenal metastasis before study inclusion is allowed (one extra-cerebral metastasis must be available for SBRT) * Able to understand and give written informed consent and comply with study procedures * Age ≥18 years * ECOG Performance Status 0-1 * Availability of tumour tissue for translational research * Adequate haematological, renal and liver function Exclusion Criteria: * Prior chemotherapy, radiotherapy or therapeutic surgery for NSCLC (an exception is the resection of one single CNS or adrenal metastasis, as above) * Activating driver mutation: epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK), proto-oncogene receptor tyrosine kinase (ROS1) * More than three distant metastases * Brain metastases not amendable for radiosurgery or neurosurgery * Extracranial metastatic locations such as malignant ascites, pleural or pericardial effusion, diffuse lymphangiomatosis of skin or lung, diffuse bone marrow metastasis, abdominal masses/abdominal organomegaly, iden…