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