Radiotherapy Combined With Thymosin for Metastatic NSCLC Patients Who Showed Stable Disease After First Line TKI Therapy

Inclusion Criteria: * Newly diagnosed metastatic lung adenocarcinoma harboring sensitizing EGFR mutations (L858R, exon 19 deletion), and showed stable disease after 3 months TKI, evaluated twice by PET/CT scan, brain MRI, and abdomen ultrasound (≥3 measurable lesions, and these lesions haven't received local therapy) * Age 18 years or older * ECOG Performance Status 0-2 * Adequate bone marrow, liver and renal function, as specified below: Absolute Neutrophil Count (ANC) ≥ 1.5 x 109/L; Hemoglobin ≥ 8 g/dL; Platelets ≥ 100 x 109/L; Serum total bilirubin ≤ 1.5 x upper limit of normal (ULN) ; AST and ALT ≤ 2.5 x ULN or ≤ 5 x ULN if liver metastases are present; Serum creatinine ≤ 1.5 x upper limit of normal or creatinine clearance ≥ 60ml/min for patients with creatinine levels above institutional normal * For women of child-bearing potential, negative pregnancy test within 14 days prior to starting treatment * Men and women of childbearing age must be willing to use effective contraception while on treatment and for at least 3 months thereafter * Patients and their family signed the informed consents Exclusion Criteria: * Received chemotherapy before TKI therapy * Brain parenchyma or leptomeningeal disease * Concurrent malignancies other than non-melanoma skin cancer that require active ongoing treatment * Any medical co-morbidities that would preclude radiation therapy.