Concurrent Pemetrexed/Cisplatin With Pleural Intensity Modulated Radiation Therapy for Patients With Unresectable Malignant Pleural Mesothelioma

Inclusion Criteria: * Pathologically confirmed diagnosis of malignant pleural mesothelioma at MSKCC * No plans for surgical resection * Stage T1-4, N0-3, M0 * No prior radiation therapy to the chest, breast or supraclavicular fossa that would limit radiation delivery to the full prescription dose * Prior chemotherapy regimens ≤1 * Age ≥18 years * Karnofsky performance status ≥ 80% * Pulmonary function tests as follows: DLCO\>50% predicted * Adequate hematologic, hepatic, and renal function as indicated by the following laboratory values * Absolute neutrophil count ≥ 1,500/mcL * Platelets ≥ 100,000/mcL * Calculated creatinine clearance (CrCl) ≥ 45mL/min (using Cockcroft \& Gault method) * Serum total bilirubin ≤ 1.5 x upper limit of normal (ULN) (unless known Gilbert's disease) * AST (SGOT) and ALT (SGPT) ≤ 3.0 x ULN Exclusion Criteria: * Pregnant or lactating women, or men or women not using effective contraception * Patients with an active infection that requires systemic antibiotics, antiviral, or antifungal treatments * Patients with a concurrent active malignancy (with the exception of skin cancer) * Patients with serious unstable medical illness * Patients with idiopathic pulmonary fibrosis * Patients with NYHA heart failure class \>2 * Patients with only one kidney that is ipsilateral to the mesothelioma * Implanted pacemaker and/or defibrillator ipsilateral to the mesothelioma if it cannot be moved * Patients meeting the following exclusion criteria will be excluded from the MRI portion only: * Metallic implant, e.g. pacemaker, defibrillator * Unmanageable claustrophobia * High risk for nephrogenic systemic fibrosis