Activity of high dose 24 hour 5-fluorouracil infusion plus L-leucovorin in advanced colorectal cancer.

Background: Modulation of 5-fluorouracil (5-FU) by leucovorin (L-LV) in patients (pts) with advanced colorectal cancer has been demonstrated to produce a highly significant benefit over single-agent 5-FU in terms of tumor response rate, but this advantage does not translate into an evident improvement of overall survival. To improve the clinical efficacy of the 5-FU plus L-LV regimen a phase II study of weekly 24-hour high-dose 5-FU infusion with L-LV was undertaken.

Patients And Methods: Seventy advanced colorectal patients were enrolled and treated by a weekly outpatient combination regimen according to the following schedule: L-LV 100 mg/sqm by 4 hours i.v. infusion followed by 5-FU 2600 mg/sqm over a 24 hours infusion combined with a fixed dose of oral L-LV (50 mg) every 4 hours for 5 times. Forty-four pts did not receive any previous CT and 26 pts were pretreated with fluoropyrimidines.

Results: The overall objective response rate (OR) was 35.3%; 7 CR and 11 PR (42.8% OR) were observed in the group of untreated pts, and 6 PR (23% OR) were reported among previously treated pts. Major side effects were represented by diarrhoea (grade III: 26%, grade IV: 1%), hand-foot syndrome (grade III: 4%, grade IV: 1%) and mucositis (grade III: 4%); however, this did not significantly influence the therapeutic programme. Median 5-FU dose intensity was 100% and 80% at 4 weeks, 87% and 75% at 8 weeks in untreated and pretreated pts, respectively.

Conclusions: L-Leucovorin modulation of weekly short-term continuous infusion of high-dose 5-fluorouracil appeared a well-tolerated outpatient regimen; it demonstrated a high activity in advanced colorectal cancer, both in untreated pts and in pts resistant to 5-FU-based chemotherapy.