Prospective Study of Stereotactic Body Radiation Therapy for Thymoma Inoma: Therapeutic Effect and Toxicity Assessment

* Inclusion Criteria: Histologic or cytologic diagnosis of thymoma, Stage II-IV.

  * Males or females between 18 Years to 75 Years.
  * No prior SBRT, if the surgery or chemotherapy has been administered, the interval is at least above four weeks.
  * Performance status of 0, 1 on the ECOG criteria. Expected survival is above three months.
  * At least one unidimensional measurable lesion meeting Response Evaluation Criteria in Solid Tumors (RECIST. 2000).
  * Patients can have the brain / meningeal metastasis history, but the metastasis must be treated by operation or radiotherapy), and clinically stable for at least 2 months.
  * Adequate hematologic (neutrophil count \>= 1,500/uL, platelets \>= 100,000/uL), hepatic (transaminase =\< upper normal limit(UNL)x2.5, bilirubin level =\< UNLx1.5), and renal (creatinine =\< UNL) function.
  * Patient compliance that allow adequate follow-up. Informed consent from patient or patient's relative.
  * If female: childbearing potential either terminated by surgery, radiation, or menopause, or attenuated by use of an approved contraceptive method (intrauterine device \[IUD\], birth control pills, or barrier device) during and for 2 months after trial. If male, use of an approved contraceptive method during the study and 2 months afterwards. Females with childbearing potential must have a urine negative HCG test within 7 days prior to the study enrollment.
  * No concomitant prescriptions including cyclosporin A, valproic acid, phenobarbital, phenytoin, ketoconazole.
* Exclusion Criteria:

  * No pathological or cytological evidence of cancer.
  * Inability to comply with protocol or study procedures.
  * Medically uncontrolled serious heart, lung, neurological, psychological, metabolic disease Second primary malignancy that is clinically detectable at the time of consideration for study enrollment.
  * Pregnant or breast-feeding.
  * Enrollment in other study within 30 days.
  * Brain metastasis with symptoms.
  * Hypokalemic and intestinal obstruction history.