Phase III Non-Inferiority Trial: Reduced-Target vs. Full-Target IMRT After Chemo in Immunotherapy-Treated Metastatic Nasopharyngeal Cancer

This study is comparing two approaches to radiation therapy for people with advanced nasopharyngeal cancer (cancer at the back of the nose) who responded well to chemotherapy combined with immunotherapy. It tests whether a smaller, more targeted radiation field works just as well as a larger one. **You may be eligible if...** - You are between 18 and 70 years old - You have metastatic (spread) nasopharyngeal cancer and have responded (fully or partially) to chemotherapy plus a PD-1 immunotherapy drug - You have not received more than one line of prior treatment - Your performance score is 0 or 1 (able to carry out normal daily activities) **You may NOT be eligible if...** - You have malignant fluid around the lungs or another cancer - You have a known or suspected autoimmune disease including epilepsy or dementia - You have significant heart problems - You received steroids or immune-suppressing medications within the past 4 weeks Talk to your doctor to see if this trial is right for you.