Surgery is also recommended for thymoma that has not grown in three years, as the disease carries some risk of malignancy. Thymoma originates from the epithelial cells of the thymus gland and the etiology of the disease is unknown and the biological behavior is complex. The cause of thymoma is not well understood and may be genetically related. Early stage thymoma patients are asymptomatic and are often found during physical examination. When the tumor grows to a certain size, the pressure on the surrounding organs can cause chest pain, chest tightness, cough and superior vena cava obstruction syndrome. For patients with thymoma whose physical condition can tolerate surgical treatment, thymectomy is the first recommended treatment. Patients who do not undergo radical surgery or who do not tolerate surgery in advanced stages may undergo adjuvant radiation therapy or chemotherapy. When thymoma disease is diagnosed, treatment should be standardized as prescribed by the doctor.