Phase II study of metronidazole therapy for advanced colorectal carcinoma.

Thirty-two patients with advanced carcinoma of the colon or rectum were given metronidazole orally at a dose of 500-1000 mg/m2 three times a day for 7 consecutive days every 6 weeks. The dose-limiting toxic effects consisted of severe nausea, vomiting, and major motor seizures. Mild peripheral neurotoxic effects were also noted. No objective responses were noted in any of the 32 patients treated. High-dose metronidazole would not seem to have any role in the treatment of advanced colorectal carcinoma and may cause serious neurotoxicity.