This study looks at how well *proton beam radiation therapy* works for people with a type of lung cancer called non-small cell lung cancer (NSCLC). This study is for patients who have had surgery to remove the cancer but still have cancer in lymph nodes in the chest. **Proton beam radiation therapy** is a special type of radiation that targets cancer cells while trying to protect healthy cells around them. The main goal is to see if this type of treatment is safe and if it works better than regular radiation.

Here are some important things to know about the study:

• The study will last 24 months after starting the therapy.
• Participants need to give blood samples during the study.
• Participants should not have other conditions like heart disease or be pregnant.

If you are over 18 and have had surgery for lung cancer, you might be able to join. You must be willing to follow instructions and attend all study visits. If you have certain medical problems or have received certain treatments recently, you might not be eligible. Always talk to your doctor to see if joining this study is a good option for you.