PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky greater than 50% Life expectancy: Not specified Hematopoietic: WBC at least 2,000/mm3 Platelet count at least 50,000/mm3 Hepatic: No porphyria or hypersensitivity to porphyrins Bilirubin no greater than 3.0 mg/dL Alkaline phosphatase no greater than 3 times ULN SGOT no greater than 3 times ULN PT no greater than 1.5 times the upper limit of normal (ULN) Renal: Creatinine no greater than 3.0 mg/dL Other: No contraindication to endoscopy Not pregnant or nursing Fertile patients must use effective contraception