Age

70–any

Sex

ALL

Healthy volunteers

Not accepted

.≥65 years or PS 2
Patients who were diagnosed by the histologic, cytologic diagnosis of IV non-small cell lung cancer
Patients received no chemical therapy or only received targeted therapy,and there is evidence show the patent is PD
Presence of at least one index lesion measurable by CT scan or MRI
* leucocyte ≥ 3.5×109/L
* neutrophil ≥ 1.5×109/L
* platelet ≥ 80×109/L
* Hemoglobin ≥ 9g/L
* ALT and AST ≤ 2.5×ULN ,Tbil≤ 1.5×ULN
BUN≤ 1.5×ULN
Signed written informed consent

squamous carcinoma or small cell lung cancer
Patients were allergic to pemetrexed
Patients received chemotherapy before
Uncontrolled acute infection
.Uncontrolled pleural effusion
Severe symptomatic heart disease
Severe infection or metabolic disfunction
Patients with other malignant tumor
Uncontrolled brain metastases
Patients have accepted other clinical trials
Female patients during their pregnant and lactation period, or patients without contraception
* Mental disorientation of disorder
* Glucocorticoids taboo

A Study of PC Sequential Pemetrexed Single Drug Maintenance Treatment for NSCLC and Related Predictive Biomarkers