Etoposide, Cyclophosphamide, Thalidomide, Celecoxib, and Fenofibrate in Relapsed or Progressive Cancer

DISEASE CHARACTERISTICS: * Histologically confirmed cancer (at diagnosis or relapse), including any of the following: * Leukemia and/or lymphoma (closed to accrual) * Bone tumor (e.g., Ewing's sarcoma or osteosarcoma) (closed to accrual) * Neuroblastoma (closed to accrual) * High-grade glial tumor * Low-grade glial tumor * Ependymoma * Medulloblastoma and/or primitive neuroectodermal tumor (PNET) * Miscellaneous tumor (closed to accrual) * Brain stem glioma, defined as intrinsic tumors of the pons causing diffuse enlargement * Brain stem glioma that progressed after radiotherapy does not require histological confirmation * Duration of symptoms at the time of diagnosis must be \< 3 months * Symptoms should consist of cranial nerve deficits, ataxia, and/or long tract signs * Relapsed or progressive poor prognosis disease for which no available curative therapy exists PATIENT CHARACTERISTICS: * Karnofsky performance status 50-100% OR Lansky play scale 50-100% (for infants) * Life expectancy \> 2 months * Platelet count \> 75,000/mm\^3 (transfusion independent) * Absolute neutrophil count \> 1,000/mm\^3 (in patients without bone marrow disease) * Hemoglobin ≥ 9.0 g/dL * Creatinine \< 1.5 mg/dL OR creatinine clearance or glomerular filtration rate ≥ 70 mL/min * Bilirubin ≤ 1.5 mg/dL * SGPT ≤ 3 times normal * SGOT ≤ 3 times normal (4 times normal for patients on ranitidine hydrochloride) * Alkaline phosphatase ≤ 3 times normal * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective double-method contraception during and for 2 months after completion of study treatment * Must be willing to participate in the Celgene STEPS® program * Recent thromboembolic disease (e.g., deep vein thrombosis or pulmonary embolism) allowed if patient is clinically stable and the thromboembolic event occurred \> 3 weeks prior to study entry * No active infection * No active uncontrolled cardiac, hepatic, renal, or psychiatric disease ≥ grade 3 * No known allergies to sulfonamides * No concurrent illness that would obscure toxicity or dangerously alter drug metabolism * No other serious medical illness PRIOR CONCURRENT THERAPY: * See Disease Characteristics * Recovered from prior therapy * Prior chemotherapy and/or radiotherapy allowed * Prior celecoxib allowed * Prior standard-dose IV etoposide and cyclophosphamide administered in 3-week courses allowed * No prior oral therapy with etoposide, thalidomide, cyclophosphamide, or fenofibrate for \> 2 months in duration * No other concurrent investigational agents * No other concurrent nonsteroidal anti-inflammatory drugs * Concurrent steroids and/or antiseizure medications allowed