Temozolomide in Preventing Brain Metastases in Small Cell Lung Cancer

Inclusion Criteria: 1. Histological or cytological diagnosis of small-cll lung cancer histology 2. 18 years or older 3. Eastern Cooperative Oncology Group (ECOG) Performance Status no more than 2 4. Local stage SCLC without distant metastases 5. After 1st-line chemotherapy (EP or IP) at least 4 cycles 6. After radical radiotherapy for primary tumor and lymph node drainage area:including concurrent or sequence chemoradiotherapy 7. CR or PR assessment by RECIST(1.0) before randomized 8. Haemoglobin 10.0 g/dl, Absolute neutrophil count (ANC) 1.5\^9/L, platelets 100 x 10\^9/L 9. Total bilirubin 1.5 x upper limit of normal (ULN) alanine aminotransferase (ALT) and aspartate aminotransferase (AST) \< 2.5 x ULN in the absence of liver metastases, or \< 5 x ULN in case of liver metastases 10. Creatinine clearance 60ml/min (calculated according to Cockcroft-gault formula) Exclusion Criteria: 1. Mixed non-small cell lung cancer histology 2. Neck and supraclavicular lymph node metastasis 3. Be allergic to temozolomide or intolerable to radiotherapy 4. Any unstable systemic disease 5. Pregnant or lactating women