DISEASE CHARACTERISTICS: Histologically proven advanced solid tumor or lymphoma that is refractory to standard therapy or for which no standard therapy exists or for which the drugs used in this regimen constitute standard therapy Brain metastasis eligible provided: Evidence of neurologic improvement or normalization No evidence of radiographic progression after appropriate therapy Steroid dose stable (if given)

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0 or 1 Life expectancy: Greater than 3 months Hematopoietic: Absolute granulocyte count at least 2,000/mm2 Platelet count at least 100,000/mm2 Hepatic: Bilirubin no greater than 1.5 mg/dL Transaminases less than 3 times normal Renal: Creatinine no greater than 1.5 mg/dL OR Creatinine clearance at least 60 mL/min Cardiovascular: No myocardial infarction within 6 months No history of congestive heart failure No uncontrolled angina No uncontrolled arrhythmia Other: No concurrent medical illness or active infection that would render treatment unsafe Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: Prior topotecan, paclitaxel, and carboplatin allowed if progression observed greater than 3 months after last dose No prior mitomycin or nitrosoureas No more than 1 prior chemotherapy regimen At least 4 weeks since chemotherapy and recovered (alopecia allowed) Endocrine therapy: Not specified Radiotherapy: No prior radiotherapy to more than 25% of bone marrow At least 4 weeks since radiotherapy and recovered (alopecia allowed) Surgery: Not specified