Phase I study of 5-fluorouracil administered by protracted venous infusion, leucovorin, and pelvic radiation therapy

BACKGROUND. This study was designed to assess the toxicity of pelvic radiation therapy, 5-fluorouracil (5-FU) administered by protracted venous infusion, and leucovorin. METHODS. Pelvic radiation therapy consisted of 50.4-54 gray (Gy) administered in 28-30 fractions. Systemic treatment consisted of leucovorin (10 mg daily) administered orally and protracted venous infusion of 5-FU. The initial daily 5-FU dose was 150 mg/m². Dose escalations were planned in increments of 25 mg/m². RESULTS. Forty eligible patients were registered, of whom 37 were evaluable for chemoradiotherapy- related toxicity. Grade 3 or 4 toxicity secondary to radiation therapy, protracted venous infusion of 5-FU, and leucovorin occurred in 2 of 17 patients at a daily 5-FU dose of 150 mg/m², in 5 of 10 patients at a daily 5-FU dose of 175 mg/m², and in 5 of 10 patients at a daily 5-FU dose of 200 mg/m². Diarrhea was dose-limiting in 7 of 8 patients with Grade 4 toxicity. Venous thrombosis, a treatment-related complication not directly related to chemotherapy or radiation therapy, occurred in 5 of the 40 patients entered into this study. Four thromboses occurred at the site of a central catheter. No thrombotic complications occurred in the last 7 patients, who were given warfarin orally (1 mg daily) during treatment. CONCLUSIONS. Toxicity due to radiation therapy, protracted venous infusion of 5-FU, and leucovorin when 5- FU is given daily at a dose of 150 mg/m² is similar to that observed in current chemoradiotherapy regimens for patients with rectal carcinoma. This regimen will be considered as a possible investigational treatment arm of a future trial of adjuvant therapy for rectal carcinoma patients.