[Phase II study of 590-S (1-phthalidyl-5-fluorouracil) in patients with gastrointestinal cancer. Tokyo Cancer Chemotherapy Cooperative Group].

590-S is a new masked compound of 5-fluorouracil, the antimetabolic antitumor agent of the fluorinated pyrimidine group. The safe dose for the phase II study was determined during the phase I study to be 600 mg/m2/day, equivalent to 900 mg/body/day. The phase II study involving 24 institutions was performed for the treatment of gastro-intestinal cancer. A daily dose of 900 mg was given 3 times a day after meals for more than 4 weeks. The number of registered cases was 32 with stomach cancer, 17 with colo-rectal cancer and 8 with others. 4 of the 23 completed cases with stomach cancer were judged as PR, and the response rate was 19.0%. No response was found in the cases with colo-rectal cancer. Slight side effects were observed in 14 of the 44 evaluable cases. Most of these were gastro-intestinal disorders.