Phase II Study of Alimta (Pemetrexed) Treatment of Advanced Thymoma and Thymic Carcinoma

Inclusion Criteria: * Histologically confirmed invasive, recurrent or metastatic thymoma or thymic carcinoma not amenable to potentially curative therapy by surgery. Original biopsy of tumor is sufficient for diagnoses unless otherwise clinically indicated. * Patients must have measurable disease with at least one bidimensional measurable lesion. Any scans or x-rays used to document measurable disease must be obtained with 6 weeks prior to registration. * Patients may have had prior chemotherapy for metastatic disease * Adequate organ function as defined by: bili \</=1.5; calc. crt clr of \>/=45; hematologic-granulocytes \>/=1500 \& plt \>/=100K. * Patients who are receiving a stable dose of corticosteroids for myasthenia gravis are eligible. * ECOG performance status of 0 or 1 Exclusion Criteria: * Acute intercurrent infection or complications * pregnancy or lactating patients * Inability to interrupt aspirin or other nonsteroidal anti-inflammatory agents for a 5-day period (8-day period for long-acting agents. * Presence of clinically relevant third-space fluid collections that cannot be controlled by a procedure