Cisplatin, fluorouracil, and high-dose leucovorin for recurrent or metastatic head and neck cancer.

We added high-dose oral leucovorin to the combination of cisplatin and fluorouracil (5-FU) to assess the efficacy of this regimen in the treatment of patients with head and neck cancer. Cisplatin, 100 mg/m2, was followed by a 5-FU continuous infusion at 600 mg/m2/d for five days. Leucovorin, 50 mg/m2, was administered at the start of cisplatin and every six hours throughout the duration of the 5-FU infusion. The dose of 5-FU was escalated to 800 mg/m2 and 1,000 mg/m2 according to observed toxicity. In a second phase of the study, the dose of leucovorin was escalated to 50 mg/m2 every four hours. A total of 25 patients were registered: 23 had recurrent disease after extensive prior treatment; and two had newly diagnosed metastatic disease. The maximally tolerated dose of 5-FU was 800 mg/m2/d with leucovorin administered every six hours. Toxicities at that level included mild to moderate myelosuppression and dose-limiting mucositis in the previously irradiated field. Identical toxicities were observed when administering 800 mg/m2/d of 5-FU with leucovorin every four hours. Eighteen patients were evaluated for response: one had a pathologic complete response; nine had a partial response (including four who received prior cisplatin and 5-FU as induction chemotherapy); and eight patients failed to respond. The mean peak and trough plasma leucovorin concentrations were 2.61 (+/- 1.07) mumol/L and 2.46 (+/- 0.95) mumol/L with administration of the drug every six hours, and 2.75 (+/- 2.15) mumol/L and 2.52 (+/- 1.48) mumol/L with administration every four hours. We conclude that the combination of cisplatin, 5-FU, and leucovorin has activity in the treatment of recurrent head and neck cancer. The maximally tolerated dose of 5-FU in this study was 800 mg/m2/d, with mucositis in previously irradiated sites being dose-limiting. Plasma leucovorin concentrations exceeding 1 mumol/L are achieved following oral administration of this drug.