Proton Radiation Therapy With Cisplatin and Etoposide Followed by Surgery in Stage III Non-Small Cell Lung Cancer

This research study is looking at an alternative way of delivering radiation therapy with protons. Protons are tiny particles with a positive charge that can be controlled to travel a certain distance and stop inside the body. In theory, this allows better control of where the radiation dose is delivered as compared to photons. Information from other research studies suggests that proton radiation may help to reduce unwanted side effects from radiation and allow an increase in radiation dose that increase the odds of tumor killing. The purpose of this study is to determine the safest dose of proton radiation therapy to give in combination with standard chemotherapy in participants with Non-Small Cell Lung Cancer (NSCLC).