A randomized phase II trial of Pemetrexed or Pemetrexed plus Carboplatin followed by maintenance Pemetrexed therapy for elderly chemotherapy naive stage IIIB/IV or postoperative recurrence non-squamous non-small cell lung cancer patients

INTERVENTION: Four cycles of Pemetrexed+ Carboplatin followed by maintenance Pemetrexed in 3 weeks cycles until progression disease Four cycles of Pacritaxel followed by maintenance Pemetrexed in 3 weeks cycles until progression disease CONDITION: non‐squamous non‐small cell lung cancer PRIMARY OUTCOME: Progression Free Survival (PFS) SECONDARY OUTCOME: Response rate (RR), Disease control rate (DCR); overall survival (OS), Safety INCLUSION CRITERIA: 1) Histologically or cytologically confirmed nonsqamous non‐small cell lung cancer 2) Stage III/VI without any indications for radiotherapy, or recurrent disease after surgery 3) No prior chemotherapy or oral postoperative adjuvant chemotherapy stopped more than one month before 4) Patients who have measurable lesion 5) ECOG PS 0‐1 6) Patients aged 75‐84 7) No prior chemotherapy for primary lesion 8) No prior chemotherapy nor radiation therapy for other cancers 9) Patients are excepted to live at least 3 months 10) Adequate organ function, evaluated within 14 days before enrollment WBC >=4,000/mm3 Neu >=2,000/mm3 Plt >=100,000/mm3 Hb>=9.0g/dl AST<=100IU/l, /ALT<=100IU/l T.Bil<=2.0mg/dl sCr<=1.0mg/dl SpO2>= 90% or PaO2>= 60torr 11) Written informed consent from the patients