Study on Proton Radiotherapy of Thymic Malignancies

This study is examining whether proton beam radiation therapy — a precise type of radiation that targets tumors while sparing surrounding healthy tissue — is safe and effective for treating rare cancers of the thymus (a gland in the chest). It includes patients who had surgery and those who did not. **You may be eligible if...** - You have been diagnosed with thymoma or thymic carcinoma (confirmed by biopsy) - You had surgery but your cancer was advanced (stage II–IVa) or your surgeon could not remove all the cancer - You could not or chose not to have surgery (any stage I–IVa) - You are 18 years or older - Your lung function is adequate **You may NOT be eligible if...** - Your cancer has spread to distant organs (stage IVb) - You are pregnant - You have another serious illness that would make treatment unsafe - Your tumor moves significantly with breathing (making precise radiation difficult) Talk to your doctor to see if this trial is right for you.