Patients with stage IIB or III colon cancer who had undergone curative resection were randomly assigned to receive UFT ( 300 mg/m ( 2 ) ) plus leucovorin ( 75 mg/day ) for 6 months ( control group , 4 weeks of treatment followed by a 1-week rest , five courses ) or for 18 months ( study group , 5 days of treatment followed by a 2-day rest , 15 courses ) .