Antineoplaston Therapy in Treating Patients With Neuroendocrine Tumor That Is Metastatic or Unlikely to Respond to Surgery or Radiation Therapy

DISEASE CHARACTERISTICS: * Histologically confirmed incurable neuroendocrine tumor that is unlikely to respond to existing therapy, meeting 1 of the following criteria: * Metastatic disease * Disease that is not curable with surgery or radiotherapy * Measurable disease by MRI or CT scan * Tumor must be at least 2 cm PATIENT CHARACTERISTICS: Age: * 18 and over Performance status: * Karnofsky 60-100% Life expectancy: * At least 2 months Hematopoietic: * WBC at least 2,000/mm\^3 * Platelet count at least 50,000/mm\^3 Hepatic: * No hepatic insufficiency * Bilirubin no greater than 2.5 mg/dL * SGOT and SGPT no greater than 5 times upper limit of normal Renal: * No renal insufficiency * Creatinine no greater than 2.5 mg/dL * No history of renal conditions that contraindicate high dosages of sodium Cardiovascular: * No uncontrolled hypertension * No history of congestive heart failure * No history of other cardiovascular conditions that contraindicate high dosages of sodium Pulmonary: * No serious lung disease, such as chronic obstructive pulmonary disease Other: * Not pregnant or nursing * Fertile patients must use effective contraception during and for 4 weeks after study participation * No active infection * No concurrent nonmalignant systemic disease * Not a high medical or psychiatric risk PRIOR CONCURRENT THERAPY: Biologic therapy: * At least 4 weeks since prior immunotherapy * No concurrent immunomodulating agents Chemotherapy: * At least 4 weeks since prior chemotherapy (6 weeks for nitrosoureas) Endocrine therapy: * Concurrent corticosteroids allowed Radiotherapy: * At least 8 weeks since prior radiotherapy Surgery: * Recovered from prior surgery Other: * Prior cytodifferentiating agents allowed * No prior antineoplastons * No other concurrent antineoplastic agents