Short communication: the addition of carbogen and nicotinamide to a palliative fractionation schedule for locally advanced breast cancer.

Tumour cell hypoxia is a recognized cause of resistance to radiotherapy. Using clinically relevant dose-fractionation schedules in a mouse tumour model, the addition of carbogen and nicotinamide to overcome chronic and acute hypoxia results in a marked increase in radioresponsiveness with a lower degree of sensitization in normal tissue. Carbogen and nicotinamide were added to the palliative radiation treatment given to six patients with locally advanced breast cancer. The aim of the pilot study was to determine if patients tolerated the addition of carbogen and nicotinamide and to assess if there was any increase in radiosensitivity of the skin. Patients received 30 Gy prescribed to the intersection dose in six fractions over 17/18 days with full skin bolus to the tumour. All patients were given 6 g of nicotinamide orally 90 min before radiation treatment. Carbogen breathing was started 5 min prior to treatment and continued during it. Patients tolerated the treatment well, with vomiting in one patient being the only side effect that could be related to the nicotinamide, and this settled with an anti-emetic. No increase in skin reaction was noted with the addition of carbogen and nicotinamide, and good tumour regression was achieved.