Trial of Pemetrexed Versus Erlotinib in Pretreated Patients With Non Small Cell Lung Cancer (NSCLC)

Inclusion Criteria: * Histologically- or cytologically- confirmed Non-Small-Cell Lung Cancer adenocarcinoma * Stage IIIB/IV * Failure to prior chemotherapy * Presence of two-dimensional measurable disease. The measurable disease should not have been irradiated * Absence or irradiated and stable central nervous system metastatic disease. * Life expectancy of more than 3 months * Tissue sample desired for genomic study * Age ≥ 18 years * Performance status (WHO) \< 3 * For patients \> 65 years old: "non-frail" according to comprehensive geriatric assessment * Adequate bone marrow function (absolute neutrophil count \> 1000/mm\^3, platelet count \> 100000/mm\^3, hemoglobin \> 9gr/mm\^3) * Adequate liver (bilirubin \< 1.5 times upper limit of normal and SGOT/SGPT \< 2 times upper limit of normal) and renal function (creatinine \< 2mg/dl) * Presence of a reliable care giver for patients \> 65 years old * Informed consent. Exclusion Criteria: * Psychiatric illness or social situation that would preclude study compliance * Other concurrent uncontrolled illness * Other invasive malignancy within the past 5 years except nonmelanoma skin cancer