Background and purpose: Causes of failure of radiotherapy in squamous cell carcinoma of the head and neck probably include repopulation and hypoxia. Very accelerated schedules such as continuous hyperfractionated accelerated radiation therapy (CHART) overcome the repopulation problem but allow limited time for reoxygenation, so a hypoxic-cell sensitizer may be especially beneficial. Nimorazole is the only such agent to have shown a significant effect in a randomized controlled trial in head and neck cancer. Accordingly we studied the combination of CHART and nimorazole.
Methods: Sixty-one patients with advanced stage III (21) or IV (40) squamous cell carcinoma of the head and neck unsuitable for surgery were treated in a phase II study of the combination. The radiation dose was 56.75 Gy in 36 fractions in 12 consecutive days. Nimorazole was administered orally or enterally 90 min before radiotherapy at a dose of 1.2, 0.9, and 0.6 g/m(2) with the first, second and third daily fractions, respectively. This dosage consistently yielded plasma concentrations above 30 microg/ml.
Results: All the patients have been followed for a minimum of 2 years since treatment. Loco-regional control at 2 years is 55%, stage III 62% and stage IV 50%. Normal tissue effects were the same as those previously seen with CHART, except for a possible slight increase in acute skin reaction. Nimorazole toxicity was somewhat greater than with once daily administration in previous studies. Grade 3 nausea or vomiting occurred in 22% of patients. Two patients developed grade 1 peripheral neuropathy, and one patient died during treatment of encephalopathy, which was probably an idiosyncratic reaction to the drug.
Conclusions: Local control rates are higher than those previously seen with CHART, suggesting a positive effect of nimorazole. Further studies of hypoxia-modifying agents with accelerated radiotherapy are warranted, and nimorazole is the simplest of these.