Cisplatin With or Without Pemetrexed Disodium in Treating Patients With Malignant Mesothelioma of the Pleura That Cannot be Removed by Surgery

DISEASE CHARACTERISTICS: Histologically confirmed malignant mesothelioma of the pleura not amenable to curative surgery Must be radiologically accessible Unidimensionally or bidimensionally measurable disease Pleural effusions or positive bone scan not considered measurable No brain metastases PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky 70-100% Life expectancy: At least 12 weeks Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hemoglobin at least 9 g/dL Hepatic: Bilirubin no greater than 1.5 times upper limit of normal (ULN) Alkaline phosphatase, AST, and ALT no greater than 3.0 times ULN (no greater than 5 times ULN with liver involvement) Albumin at least 3.0 g/dL Renal: Creatinine clearance at least 45 mL/min Other: No serious systemic disorders that may preclude study No prior primary malignancy within the past 5 years except carcinoma in situ of the cervix or adequately treated basal cell carcinoma of the skin No obvious malnourishment or greater than 10% weight loss within 6 weeks prior to study No active infection Not pregnant or nursing Fertile patients must use effective contraception during and for 3 months after study PRIOR CONCURRENT THERAPY: Biologic therapy: Prior immunomodulators allowed for pleurodesis No concurrent immunotherapy Chemotherapy: No prior systemic chemotherapy At least 1 week since prior bleomycin for pleurodesis Prior intracavitary cytotoxic drugs allowed for pleurodesis No other concurrent chemotherapy Endocrine therapy: No concurrent hormonal anticancer therapy Radiotherapy: At least 4 weeks since prior radiotherapy to target lesion Lesion must be clearly progressive No concurrent radiotherapy Surgery: See Disease Characteristics No concurrent surgery for cancer Other: At least 4 weeks since any other prior investigational agent No concurrent aspirin or other nonsteroidal antiinflammatory drug from 2 days prior to 2 days after study (5 days prior for long acting agents such as piroxicam, naproxen, diflunisal, or nabumetone) No other concurrent experimental medications