Summary
This trial studies the side effects of pembrolizumab with or without chemotherapy in treating patients with stage IV non-small cell lung cancer that has come back after a period of improvement (recurrent) and may have spread from where it first started to nearby tissue, lymph nodes, or distant parts of the body (advanced). Immunotherapy with monoclonal antibodies, such as pembrolizumab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Drugs used in chemotherapy, such as pemetrexed and carboplatin, work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Giving pembrolizumab with or without chemotherapy may shrink the tumor in older patients with non-small cell lung cancer.