5-fluorouracil-induced small bowel toxicity in patients with colorectal carcinoma

BACKGROUND. Diarrhea and oral mucositis are the most frequently reported ga strointestinal side effects caused by 5-fluorouracil (5-FU). Diarrhea may b e severe in 10-30% of patients and is schedule-dependent. 5-FU-induced gast rointestinal toxicity predominantly affects the upper and the lower gastroi ntestinal tract. The current study describes 5-FU-induced small bowel toxic ity as an entity that to the authors' knowledge has not been reported previ ously in patients with colon carcinoma receiving 5-FU-based therapy. METHODS. The authors report a series of six patients with colorectal carcin oma who developed acute small bowel toxicity after treatment with 5-FU and leucovorin. RESULTS. Six patients developed a clinical picture of acute abdominal pain and diarrhea. Small bowel damage was documented by laparotomy in two patien ts, by colonoscopy in one patient, and by abdominal computed tomography sca n in three patients. The course was complicated by recurrence of symptoms i n one patient who was rechallenged with 5-FU and leucovorin, but the remain ing four patients were rechallenged safely with lower doses of 5-FU and leu covorin after the acute toxicity episode. A possible explanation for this t oxicity is 5-FU-induced vasospasm and/or decrease in fibrinolytic activity that results in decreased mucosal blood flow. CONCLUSIONS. 5-FU-induced small bowel toxicity is a potentially severe toxi city that may occur in patients with colon carcinoma or other malignancies who are receiving 5-FU-based therapy. [See editorial on pages 1099-100, thi s issue.] Cancer 1999;86:1129-34. (C) 1999 American Cancer Society.