The thymus, an organ located beneath the breast bone, is responsible for making some of the white blood cells called lymphocytes, which help the body fight infections. Cancer in this organ is called malignant thymoma. Patients with malignant thymoma often have other immune system diseases; symptoms include a persistent cough, muscle weakness, and chest pain. Treatment depends on the stage of the disease but may include surgery, radiation therapy, hormone therapy, or chemotherapy.
