This study is looking at a new treatment called durvalumab for people with early-stage non-small cell lung cancer (NSCLC) who have had surgery and no longer have cancer cells. Durvalumab is a type of immunotherapy that helps the immune system fight cancer. Usually, after surgery, patients are carefully monitored and only treated if cancer comes back. This study will compare durvalumab treatment with regular observation to see if it helps patients live longer and stops cancer from returning. Patients will be randomly assigned to receive durvalumab or be observed. Durvalumab is given through an IV (intravenous) every 28 days, up to 12 times. Patients will have regular check-ups and CT scans. The study lasts for 12 months, with follow-ups for 10 years. **Key Points:** - Treatment involves durvalumab IV or observation without treatment. - Study duration is 12 months, with long-term follow-ups. - Participants need to have specific eligibility, and there are potential risks with durvalumab. This study can offer new insights into improving survival rates and quality of life for lung cancer patients.