Pembrolizumab After Lung SBRT for Medically Inoperable Early Stage Non-small Cell Lung Cancer

The purpose of this study is to see whether patients who have early stage NSCLC bigger than a certain size might benefit from receiving additional medicinal drug to treat their cancer after the SBRT Surgeons and radiation doctors have understood for some time that the chances of cancer showing up in areas outside the chest are higher for patients with tumors bigger than 3 cm, (about 1 ¼ inches). However, it is not routine to offer chemotherapy or drug treatments after radiation or surgery for lung cancer for patients with early stage lung cancer. This is because giving extra treatment in the form of chemotherapy has not shown to help patients live longer. There has been reluctance to offer additional treatments, especially chemotherapy, to patients with lung cancer who could not have surgery because of their medical issues. Even if these patients were felt to be at a higher risk of their cancer coming back, there is hesitation because the treatments can be difficult to tolerate in frail patients. Recently, there have been very important advances in the kinds of drug therapy that are used for lung cancer patients. These kinds of drugs are called immunotherapy since they work with the body's immune system to fight the cancer. These drugs have been shown to make patients with advanced, incurable lung cancer, live longer and also to be very safe with very limited side effects. Because of these favorable characteristics, cancer specialists are interested in using these drugs for patients with curable cancer and for patients who may be too fragile for traditional chemotherapy. In this way, patients who get SBRT are already known to be fragile so cancer doctors are interested in now studying this kind of drug in SBRT patients to see if it can make patients with large tumors do better. The idea of the study then is that the patient would receive their standard SBRT and if their tumor is of a certain size that makes the risk of the cancer showing up outside the chest higher than routine, they would be considered for getting the immunotherapy drug. Pembrolizumab is an investigational drug (also known as Keytruda), which has been approved by the FDA for use in certain types of skin cancer (melanoma), and for use in certain types of head and neck cancer. However, it has not been approved for use in other cancers such as newly diagnosed early stage NSCLC. It is FDA approved for advanced NSCLC, that is people who have already had some chemotherapy and their disease has worsened. Pembrolizumab is a monoclonal antibody that binds to the surface of some cells of the immune system and activates them against cancer cells. It is not chemotherapy.