COMBINATION OF FRACTIONATED-IRRADIATION WITH NICOTINAMIDE AND CARBOGEN IN R1H-TUMORS OF THE RAT AND ITS PULMONARY METASTASES

Background and purpose: The combination of radiotherapy with nicotinam ide and carbogen is a promising method to improve treatment outcome. T he aim of the present study was to investigate its effect on rat lungs , the R1H-tumour and its pulmonary metastases. Materials and Methods: Subcutaneous tumours and artificially induced pulmonary metastases of the rhabdomyosarcoma R1H of the rat were treated either with fractiona ted irradiation alone or in combination with nicotinamide and carbogen . Local metastatic control, net growth delay and lethal lung damage we re used as endpoints. Results: Radiosensitivity of the lungs of WAG/Ri j rats increased by a factor of 1.13, while no positive effect of the combined treatment either on subcutaneous R1H-tumours or on pulmonary metastases could be detected. This resulted in a therapeutic loss of 1 8% (P = 0.003). Conclusion: The results indicate that deleterious effe cts of the combination of radiotherapy with nicotinamide and carbogen cannot be excluded under all circumstances. (C) 1997 Elsevier Science Ireland Ltd.