Testing the Addition of Radiation Therapy to the Usual Immune Therapy Treatment (Atezolizumab) for Extensive Stage Small Cell Lung Cancer, The RAPTOR Trial

Inclusion Criteria: * Any confirmation (cytologic, histologic, or pathologic) of extensive stage small cell lung cancer at any site, either primary or metastases * Partial response (PR) or stable disease (SD) after 4-6 cycles of etoposide/platinum (E/P) doublet plus atezolizumab by re-staging scans (positron emission tomography \[PET\]/computed tomography \[CT\] scan, diagnostic CT scan, magnetic resonance imaging \[MRI\] optional per treating physician); atezolizumab should continue through randomization. Patients must be randomized within 9 weeks of last dose of etoposide/platinum (if not receiving PCI) or 6 weeks from completion of prophylactic cranial irradiation (PCI) * NOTE: Patients must have at least 3 cycles of E/P plus atezolizumab. They can have one cycle of induction E/P without concurrent atezolizumab if unable to receive concurrent E/P combined with atezolizumab for all cycles of induction therapy * Patients must have measurable disease (per Response Evaluation Criteria in Solid Tumors \[RECIST\]) and 3 or fewer observable liver metastases and no evidence of progressive disease (per RECIST) at time of enrollment * At time of enrollment after induction E/P chemotherapy and atezolizumab, if there is a pleural effusion, patients will be eligible if thoracentesis is cytologically negative or if pleural fluid is too small a volume to effectively sample by thoracentesis and does not show increased metabolic activity on CT/PET imaging * Appropriate stage for study …