Cisplatin, 5-fluorouracil, and high-dose oral leucovorin for advanced head and neck cancer.

Both cisplatin and leucovorin may increase the activity of 5-fluorouracil (5-FU) by increasing the intracellular concentration of reduced folates. Therefore, a Phase I study was conducted in patients with recurrent or metastatic head and neck cancer in which high doses of oral leucovorin were added to the combination of cisplatin and 5-FU. Patients received intravenous cisplatin 100 mg/m2 on day 1, followed by a continuous intravenous infusion of 5-FU at 600 mg/m2/day for 5 days. Leucovorin 50 mg/m2 orally was administered from the start of the cisplatin infusion and then every 6 hours throughout the 5-FU infusion. The dose of 5-FU was increased to 800 mg/m2/day and 1 g/m2/day according to observed toxicity. In a second phase of the study, the dose of leucovorin was increased to 50 mg/m2 orally every 4 hours. Twenty-five patients were registered: 23 had recurrent head and neck cancer after extensive treatment; two had newly diagnosed metastatic disease. The maximum tolerated dose of 5-FU was 800 mg/m2/day with leucovorin administered every 6 hours. Toxicities at that level included mild-to-moderate myelosuppression. Mucositis in the previously irradiated field prevented the further increase of the 5-FU dose to 1 g/m2/day. Identical toxicities were observed when administering 5-FU at 800 mg/m2/day with 50 mg/m2 of leucovorin every 4 hours. Eighteen patients were evaluated for response: one had a pathologic complete response; nine had a partial response (including four who had previously received cisplatin and 5-FU as induction chemotherapy). Eight patients did not respond. The median survival for all 25 patients was 6.5 months. It was concluded that the combination of cisplatin, 5-FU, and leucovorin is active in the treatment of recurrent head and neck cancer. The maximum tolerated dose of 5-FU in previously treated patients is 800 mg/m2/day, with mucositis being the dose-limiting toxicity. Further investigation of this regimen as neoadjuvant chemotherapy in previously untreated patients with locally advanced head and neck cancer is in progress.