Effect of 1-hexylcarbamoyl-5-fluorouracil on spontaneous mammary adenocarcinoma of mice.

The antitumor activity of 1-hexylcarbamoyl-5-fluorouracil (HCFU) in various schedules of long-term oral administration was examined in spontaneous mammary adenocarcinoma of SHN mice, an autochthonous tumor system. In the control group, the average time to local recurrence and average longevity after surgical intervention were 21 and 48 days, respectively. Oral administration of HCFU at 200 approximately 300 mg/kg/day, 3 times a week for 5 consecutive days every 2 or 3 weeks was markedly effective against the adenocarcinoma. The optimal schedule was 20 administrations of HCFU at 300 mg/kg/day, 3 times a week. The average time to local recurrence after the operation was increased to 200% and average postoperative survival was also prolonged to 150%. Growth of the tumors was slower and lung metastases at autopsy were found to be suppressed by HCFU. The effect of HCFU in delaying local recurrence and prolonging longevity was slightly affected by the schedule of administration.