PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky 70-100% Life expectancy: Not specified Hematopoietic: WBC at least 3,000/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin, SGOT, and alkaline phosphatase less than 2 times normal Renal: Creatinine less than 1.6 mg/dL Creatinine clearance at least 50 mL/min Other: No other concurrent active invasive malignancy No seafood allergy No positive stool guaiac (excluding hemorrhoids)