This study evaluates the optimal intervention time of radiotherapy for oligometastatic stage iv lung cancer.

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