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