Pemetrexed Disodium and Gemcitabine in Treating Patients With Stage IIIB or Stage IV Non-Small Cell Lung Cancer

DISEASE CHARACTERISTICS: * Histologically or cytologically confirmed non-small cell lung cancer (NSCLC) * Stage IIIB (with controlled pleural effusion) OR stage IV disease * At least 1 measurable lesion whose longest diameter is ≥ 20 mm by conventional techniques OR ≥ 10 mm by spiral CT scan * No medically significant third-space fluid collection (e.g., ascites or pleural effusions) that cannot be controlled by drainage or other procedures * No documented brain metastases unless all of the following criteria are met: * Successful local therapy has been completed * At least 2 weeks since prior corticosteroids * Brain imaging required for symptomatic patients only (to rule out brain metastases) * Concurrent enrollment in clinical trial MCCRC-RC0527 required PATIENT CHARACTERISTICS: * Life expectancy ≥ 12 weeks * ECOG performance status 0-1 * Absolute neutrophil count ≥ 1,500/mm³ * Platelet count ≥ 100,000/mm³ * Hemoglobin ≥ 9.0 g/dL * Bilirubin ≤ 1.5 times upper limit of normal (ULN) * Alkaline phosphatase ≤ 3 times ULN * AST and ALT ≤ 3 times ULN (5 times ULN for liver involvement) * Creatinine clearance ≥ 45 mL/min * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * Able to take folic acid, cyanocobalamin (vitamin B12) supplementation, or dexamethasone and corticosteroids * Able to interrupt intake of aspirin and nonsteroidal anti-inflammatory agents for a total of 5 days * No severe and/or uncontrolled medical conditions, including any of the following: * Hypertension, labile hypertension, or history of poor compliance with antihypertensive medication * Angina pectoris * Congestive heart failure within the past 3 months, unless ejection fraction \> 40% * Myocardial infarction within the past 6 months * Cardiac arrhythmia * Diabetes * Interstitial pneumonia or extensive and symptomatic interstitial fibrosis of the lung * New York Heart Association class III or IV heart disease * Clinically significant infection * No other serious medical condition or illness that would preclude study participation * No peripheral neuropathy ≥ grade 2 * No other malignancy within the past 5 years except nonmelanomatous skin cancer, carcinoma in situ of the cervix, or low-grade (Gleason score ≤ 6) localized prostate cancer * No significant weight loss (≥ 10%) within the past 6 weeks * No investigator site personnel directly affiliated with the study, or immediate family (i.e., spouse, parent, child, or sibling, whether biological or legally adopted) * No employees of Eli Lilly (i.e., employees, temporary contract workers, or designees responsible for conducting the study) * Immediate family of Eli Lilly employees may participate in Eli Lilly-sponsored clinical trials, but are not permitted to participate at an Eli Lilly facility PRIOR CONCURRENT THERAPY: * See Disease Characteristics * At least 2 weeks since prior corticosteroids * At least 4 weeks since prior radiation therapy involving \> 25% of the bone marrow and recovered * At least 30 days since prior investigational therapy * No prior radiation therapy to the whole pelvis * No prior systemic chemotherapy for advanced non-small cell lung cancer * No prior pemetrexed disodium and/or gemcitabine hydrochloride * No prior or concurrent sorafenib tosylate and/or temsirolimus * No concurrent Hypericum perforatum (St. John's wort) * No other concurrent antitumor therapy * No concurrent agents that stimulate thrombopoiesis * Concurrent palliative radiation therapy allowed * Concurrent corticosteroids allowed for adrenal insufficiency or severe nausea and vomiting