DISEASE CHARACTERISTICS: Histologically proven solid tumors or lymphoma refractory to standard therapy or for which no standard therapy exists Brain metastases allowed if following criteria met: Asymptomatic Received prior therapy for brain metastases Stable for at least 2 months No concurrent steroid therapy

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: CALGB 0-2 Life expectancy: Not specified Hematopoietic: Granulocyte count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic and Renal: Albumin at least 2.5 g/dL Prothrombin time less than 1.6 For patients without prior pelvic radiotherapy: AST at least 3 times upper limit of normal (ULN) OR Bilirubin 1.0 - 7.0 mg/dL with any AST OR Creatinine 1.6 - 5.0 mg/dL For patients with prior pelvic radiotherapy: AST less than 3 times ULN AND Bilirubin less than 1.0 mg/dL AND Creatinine less than 1.6 mg/dL Other: Not pregnant or nursing

PRIOR CONCURRENT THERAPY: Biologic therapy: No concurrent colony stimulating factors Chemotherapy: At least 4 weeks since prior chemotherapy (at least 6 weeks since melphalan or mitomycin) At least 3 months since suramin No prior nitrosoureas or irinotecan Endocrine therapy: No concurrent steroids (except as antiemetic for chemotherapy) Radiotherapy: At least 4 weeks since prior radiotherapy Surgery: At least 4 weeks since major surgery Other: No concurrent medications known to affect hepatic or renal function (e.g., antiseizure medication or nonsteroidal antiinflammatory drugs)