OBJECTIVES: I. Determine the objective response rate of a 120 hour continuous infusion of aminocamptothecin (9-AC) in chemotherapy naive patients with adenocarcinoma of the stomach or gastroesophageal junction. II. Characterize the nature of the toxicity of 9-AC on this schedule in this patient population. III. Determine the duration of response, time to progression, and survival of this patient population. IV. Study the pharmacokinetics and pharmacodynamics of 9-AC on this schedule in these patients.