A phase III trial has demonstrated that in advanced non-small cell lung cancer (NSCLC) cisplatin/ pemetrexed provides similar efficacy with better tolerability and more convenient administration than cisplatin/gemcitabine. Moreover,this trial showed survival differences based on histologic type. The investigators want to research some biomarkers that can predict clinical outcomes.

Inclusion Criteria:

1. Chemotherapy-naive patients with histologically or cytologically confirmed adenocarcinoma and large-cell carcinoma, classified as stage IIIB not amenable to curative treatment or stage IV
2. With at least one unidimensionally measurable lesion according to the Response Evaluation Criteria in Solid Tumors;
3. with an Eastern CooperativeOncology Group performance status of 0 or 1,
4. At least 18 years of age
5. adequate bone marrow reserve and organ function including calculated creatinine clearance 45 mL/min based on the standard Cockcroft and Gault formula.
6. Prior radiation therapy was permitted if it was completed at least 4 weeks before study treatment
7. patients had fully recovered from its acute effects.

Exclusion Criteria:

1. peripheral neuropathy > National Cancer Institute Common Toxicity Criteria grade 1
2. progressive brain metastases,
3. uncontrolled third-space fluid retention before study entry.
4. Patients unable to interrupt aspirin and other nonsteroidal anti-inflammatory drugs or if they were unable or unwilling to take folic acid, vitamin B12, or corticosteroids.