DISEASE CHARACTERISTICS:

• Histologically or cytologically confirmed solid tumors

  • Neuroblastoma
  • Ewing's sarcoma/peripheral primitive neuroectodermal tumor (PNET)(Ewing's sarcoma closed to accrual as of 5/19/03)
  • Osteosarcoma (closed to accrual as of 5/19/03)
  • Rhabdomyosarcoma
  • Other extracranial solid tumors

  • CNS/brain tumors:

    • Medulloblastoma/PNET
    • Ependymoma
    • Brainstem glioma
    • Other CNS tumors
  • Histological verification may be waived for brainstem glioma and classic optic glioma, but biopsy recommended OR

• Histologically or cytologically proven non-Hodgkin's lymphoma

  • Refractory to standard treatment and no curative therapy available
• Measurable disease

PATIENT CHARACTERISTICS:

Age:

• 21 and under at time of original diagnosis

Performance status:

• Karnofsky 50-100% in patients over 10 years of age
• Lansky 50-100% in patients age 10 and under

Life expectancy:

• At least 8 weeks

Hematopoietic:

• Absolute neutrophil count greater than 1,000/mm^3
• Platelet count greater than 75,000/mm^3
• Hemoglobin greater than 8.0 g/dL

Hepatic:

• Bilirubin normal for age
• SGPT less than 2.5 times upper limit of normal
• Amylase normal
• Lipase normal

Renal:

• Creatinine normal for age OR
• Glomerular filtration rate at least 60 mL/min

Other:

• No concurrent uncontrolled infection
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception during and for 6 months after study participation

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• Recovered from prior immunotherapy

Chemotherapy:

• At least 6 weeks since prior nitrosourea and recovered
• Recovered from any other prior chemotherapy
• No more than two prior chemotherapy regimens

Endocrine therapy:

• CNS tumor patients receiving dexamethasone must be on stable or decreasing dose at least 2 weeks prior to study entry

Radiotherapy:

• At least 6 weeks since prior extended radiotherapy and recovered
• No prior total body irradiation

Surgery:

• Prior radiosurgery allowed

Other:

• No concurrent use of the following foods or medications:

  • Grapefruit juice
  • Erythromycin
  • Azithromycin
  • Clarithromycin
  • Rifampin and analogues
  • Fluconazole
  • Ketoconazole
  • Itraconazole
  • Cimetidine
  • Cannabinoids (marijuana or dronabinol)
  • Leukotriene inhibitors (e.g., zafirlukast and zileuton)
• No other concurrent anticancer or investigational agents