A Phase 3, Randomized, Placebo-Controlled Clinical Study to Evaluate the Safety and Efficacy of Stereotactic Body Radiotherapy (SBRT) with or without Pembrolizumab (MK-3475) in Participants with Medically Inoperable Stages I or IIA Non Small Cell Lung Cancer (NSCLC)(KEYNOTE-867) MK 3475-867
- To compare the Event Free Survival (EFS). - Hypothesis: SBRT + pembrolizumab prolongs EFS compared to SBRT + placebo. - To compare Overall Survival (OS). - Hypothesis: SBRT + pembrolizumab prolongs OS compared to SBRT + placebo.