This Phase II study is to determine the efficacy and safety of MR-Linac Guided Radiotherapy in patients with inoperable mediastinal tumors.

This Phase II study is to determine the efficacy and safety of MR-Linac Guided Radiotherapy in patients with inoperable mediastinal tumors.

Patients will receive radiotherapy on the MR-Linac treatment machine. The primary end point is 2-year local-recurrence free survival. The secondary end points are objective response rate, 2-y PFS, 2-y OS, safety of treatment, dose coverage of targets and dose to normal organs.

Inclusion Criteria:

• Aged 18-75 years
• Histologically or cytologically confirmed mediastinal cancer
• Patients with inoperable mediastinal lesions
• Eastern Cooperative Oncology Group (ECOG) performance status 0-1
• Normal function of organs and bone marrow within 14 days: Total bilirubin 1.5 times or less the upper limits of normal (ULN); AST and ALT 1.5 times or less the ULN; absolute neutrophil count≥ 500 cells/mm3; creatinine clearance rate(CCR) ≥45 mL/min; Platelet count≥50,000 cells/mm3; international normalized ratio(INR) ≤1.5#Prothrombin Time (PT)≤ 1.5 × ULN
• Informed-consent

Exclusion Criteria:

• Patients with contraindications for MRI
• Previous radiotherapy or excision for mediastinal tumor
• The tumor has completely approached, encircled, or invaded the intravascular space of the great vessels (e.g., the pulmonary artery or the superior vena cava)
• A cavity over 2cm in diameter of primary tumor or metastasis Bleeding tendency or coagulation disorder
• Hemoptysis (1/2 teaspoon blood/day) happened within 1 month
• The use of full-dose anticoagulation within the past 1 month
• Severe vascular disease occurred within 6 months
• Gastrointestinal fistula, perforation or abdominal abscess occurred within 6 months
• Hypertensive crisis, hypertensive encephalopathy, symptomatic heart failure (New York class II or above), active cerebrovascular disease or cardiovascular disease occurred within 6 months
• Uncontrolled hypertension (systolic > 150mmHg and/or diastolic > 100mmHg)
• Major surgery within 28 days or minor surgery or needle biopsy within 48 hours
• Urine protein 3-4+, or 24h urine protein quantitative >1g
• Severe uncontrolled disease
• Uncontrollable seizure or psychotic patients without self-control ability
• Women in pregnancy, lactation period
• Other not suitable conditions determined by the investigators