Pemetrexed, Cisplatin, and Vitamin B12 in Treating Patients With Mesothelioma of the Chest That Cannot Be Removed by Surgery

RATIONALE: Pemetrexed may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Drugs used in chemotherapy, such as cisplatin, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving pemetrexed together with cisplatin and vitamin B12 may kill more tumor cells. PURPOSE: This phase II clinical trial is studying how well giving pemetrexed together with cisplatin and vitamin B12 works in treating patients with mesothelioma of the chest that cannot be removed by surgery.

DISEASE CHARACTERISTICS: Inclusion criteria: * Histologically confirmed pleural mesothelioma * Unresectable disease Exclusion criteria: * Clinically detected pleural effusion or ascites that cannot be controlled by drainage or other procedures PATIENT CHARACTERISTICS: Inclusion criteria: * WHO performance status 0-2 * Life expectancy \> 3 months * Absolute neutrophil count ≥ 1,500/mm\^3 * Platelet count ≥ 100,000/mm\^3 * Creatinine clearance \> 45 mL/min * Total bilirubin ≤ 1.5 times upper limit of normal (ULN) * Transaminases ≤ 3 times ULN (5 times ULN if liver metastases) * Not pregnant or nursing * Fertile patients of must use effective contraception during and for 6 months after completion of study treatment Exclusion criteria: * Hypersensitivity to pemetrexed disodium or any of its excipients * Peripheral neuropathy ≥ grade 2 * Impossible to receive study therapy due to geographical, social, familial, or psychological reasons PRIOR CONCURRENT THERAPY: Inclusion criteria: * At least 28 days since prior radiotherapy (21 days for injected radiotherapy) Exclusion criteria: * Prior chemotherapy * Prior yellow fever vaccine * Inability to discontinue aspirin (\> 1.3 g/day) or NSAIDs for 2 days prior to, during, and 2 days after day 1 of each course of study therapy * Concurrent participation in another clinical study