Stereotactic Radiotherapy for Oligo-Progressive Metastatic Cancer (The STOP Trial)

Inclusion Criteria: * Age 18 or older * Willing to provide informed consent * Histologically confirmed Non-Small Cell Lung Cancer (NSCLC) with metastatic disease detected on imaging. Biopsy of metastasis at some time point prior to enrollment is preferred, but not required. * Eastern Cooperative Oncology Group (ECOG) performance status 0-2 * Life expectancy \> 3 months * Patient has received treatment with systemic therapy (either cytotoxic or targeted, including maintenance therapies) during the past 6 weeks. This most recent systemic therapy agent must have been delivered for a total of at least 3 months, with an initial partial response (PR), complete response (CR) or stable disease (CR) prior to the development of oligo-progressive lesions. * Oligoprogression, defined as Response Evaluation Criteria in Solid Tumors (RECIST)-documented progression in up to 5 individual lesions, with no previous radiation or radiofrequency ablation to those sites. Oligoprogression may be defined as: * Progression of an individual metastasis according to RECIST 1.1 criteria * Unambiguous development of a new metastatic lesion at least 5mm in size * Progressive enlargement of a known metastasis on 2 consecutive imaging studies 2- 3 months apart with a minimum 5mm increase in size from baseline * All sites of oligoprogression can be safely treated * Maximum 3 progressing metastases in any single organ system (i.e. lung, liver, brain, bone), and the total number of metastases must be 5 or less…