Background: This study was designed to determine the efficacy and maximally tolerated dose of 5-fluorouracil when administered by chronobiologically shaped prolonged infusion in combination with radiation therapy in patients with both locally advanced and unresectable rectal carcinoma.
Methods: Eighteen sequential patients determined clinically to have either locally advanced or unresectable rectal carcinoma were treated by 4500 centigray (cGy) or 5580 cGy, respectively, combined with continuous chronobiologically modulated 5-FU infusion starting at 250 mg/m2/day, with the dose escalating in each cohort of 5 patients if no Grade 3 or higher toxicity was observed in each cohort. Imaging studies were obtained prior to and after completion of treatment.
Results: All 18 patients completed the full course of radiation therapy and all were subsequently resectable for potential cure. The maximum tolerated dose of 5-FU was 275/m2/day for 5 weeks. Seven patients had a sphincter-sparing procedure, and ten patients underwent an abdominoperineal resection, all with clear margins. Five complete pathologic responses (28%) were obtained. The average follow-up time was 12 months with a range of 6 to 37 months. With the exception of two patients, one of whom declined surgery and one of whom died of widespread disease, all of the patients have remained free of disease.
Conclusions: The combination of radiation therapy and continuous chronobiologically shaped 5-FU infusion at a dose of up to 275/m2/day is well tolerated and appears to be more effective in downsizing and possibly downstaging locally advanced and unresectable rectal carcinoma than radiation therapy alone. Longer follow-up will determine whether ultimate disease free and overall survival are improved by this method.