Phenylbutyrate in Treating Patients With Refractory Solid Tumors or Lymphoma

DISEASE CHARACTERISTICS: * Histologically or cytologically confirmed solid tumor or lymphoma that is progressive or refractory to conventional therapy or for which no effective therapy is known * Priority given to hormone-refractory prostate cancer and melanoma * No untreated CNS metastases * Head CT not required in the absence of clinical signs or symptoms but recommended for metastatic melanoma PATIENT CHARACTERISTICS: * Age: 18 and over * Performance status: ECOG 0-2 * Life expectancy: At least 3 months * WBC greater than 2,000/mm3 OR absolute neutrophil count greater than 1,500/mm3 * Platelet count greater than 100,000/mm3 * Hemoglobin greater than 9 g/dL * Bilirubin less than 1.5 mg/dL * AST/ALT less than 1.5 times normal * Creatinine less than 2.0 mg/dL * Obstructive uropathy allowed if relieved by nephrostomy or other appropriate device * Left ventricular ejection fraction greater than 40% by MUGA or normal by echocardiogram * No history of congestive heart failure * No uncontrolled hypertension (diastolic greater than 110 mm Hg) * Forced expiratory volume (1 second) greater than 1.5 L/min * No active infection, including HIV or viral hepatitis * No active seizure disorder * No clinical evidence of increased intracranial pressure * No baseline dementia (mini-mental exam less than 23) * No autoimmune disease, including systemic lupus erythematosus, scleroderma, or other connective tissue illness * No nonmalignant medical or psychiatric problem of sufficient severity to limit full compliance with study or to pose undue risk * Not pregnant or nursing * Adequate contraception required of fertile patients for 2 weeks prior to, during, and for 3 months after study * Normal gastrointestinal function with ability to tolerate large intake of oral volume required for phenylbutyrate administration * Patients with persistent nausea or moderate to severe anorexia may not be good candidates for study PRIOR CONCURRENT THERAPY: * Fully recovered from all prior therapy * Prior suramin allowed if serum suramin level less than 50 micrograms/mL at entry * At least 28 days since chemotherapy * No prior phenylacetate, phenylbutyrate, or antineoplaston therapy * The following may be continued during study: * Luteinizing hormone-releasing hormone agonist with evidence of tumor progression (e.g., rising prostate-specific antigen, new lesions on bone scan) despite therapy * Adrenal steroid replacement (if needed) * Dexamethasone or other steroids * At least 4-6 weeks since flutamide with evidence of PSA progression required (if possible) * At least 28 days since radiotherapy * At least 28 days since major surgery