The Optimal Intervention Time of Radiotherapy for Oligometastatic Stage IV Non-small Cell Lung Cancer（NSCLC）

Inclusion Criteria: * 18 to 75 years old , male or female * Pathologically or cytologically proven oligometastatic stage IV NSCLC non-small cell lung cancer（NSCLC） * Primary tumors can be measured * Distant organ metastases number ≤ 5 * Karnofsky score \>70,Zubrod performance status 0-1 * Estimated life expectancy of at least 12 weeks * reproductive age women should ensure that before entering the study period contraception * Hemoglobin≥10.0g/dL,WBC≥ 4000 cells/mm³,Platelet count≥100,000 cells/mm³ * Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) \< 2.5 times upper limit of normal,bilirubin normal * Creatinine normal OR creatinine clearance ≥ 60 mL/min * Patients have good compliance to treatment and follow-up of acceptance. Exclusion Criteria: * Allergic to pemetrexed, cisplatin, docetaxel and contrast medium * Distant metastases organs \> 5 * The primary tumor or lymph node already received surgical treatment (except for biopsy) * Patient who received radiotherapy for primary tumor or lymph node * Patient who received the the epidermal growth factor targeted therapy * Patient who received chemotherapy or immunotherapy * Patient who suffered from other malignant tumor * Patient who have taken other drug test within 1 month * Pregnant woman or Lactating Women and Women in productive age who refuse to take contraception in observation period * Subject with a severe allergic history or idiosyncratic * Subject with severe pulmonary and cardiopathic disease history * Refuse or incapable to sign the informed consent form of participating this trial * Drug abuse or alcohol addicted * Subject with a Personality or psychiatric diseases, people with no legal capacity or people with limited capacity for civil conduct