Prolonged metronidazole administration with protracted radiotherapy: a pilot study on response of advanced tumours.

In a pilot study, 2.5 g of metronidazole was administered in 3 divided daily doses for prolonged periods with protracted fractionated conventional radiotherapy. Total cumulative metronidazole dose was 94 g in 31 patients with head and neck carcinoma. In some others, lower dosage was used. Radiotherapy dose varied form 3000 rad in 5 patients to 7600 rad in 31 patients. Preliminary results with a minimum follow-up period of 6 months suggest enhanced tumour response without evident toxicity. The improved results, if sustained, may be speculatively explained by the combined or individual enhancement of effect due to the hypoxic radiosensitizer or by the high dose precision radiotherapy or by the specific elimination of the hypoxic tumour cells by cytotoxic effect of prolonged metronidazole administration. Controlled trials are now needed.