HALOTHANE AND ISOFLURANE ENHANCE MELANOMA TUMOR-METASTASIS IN MICE

Purpose: To investigate the incidence of tumour metastasis from Bl6 me lanoma tumour cells in experimental animals following exposure to equi potent concentrations of halothane or isoflurane, and to differentiate if exposure to one anaesthetic resulted in greater metastases than th e other. Methods: Experimental animals (C57BI mice), were randomized t o receive 1.3 MAC hours of halothane or isoflurane anaesthesia. The co ntrol group of animals received oxygen alone under identical condition s, Fifteen minutes after completion of anaesthesia, control and experi mental groups were given 1 x 10(5) Bl6 melanoma cells intravenously. A fter 21 days, all animals were autopsied, and the metastatic nodules i n their lungs were counted. The difference in the numbers of metastati c nodules between control and experimental groups oi animals was analy zed for significance by the Mann Whitney ''U test''. Results: More met astases were observed in in the animals exposed to halothane (37,28+/- 5.08, P<0.0001), or isoflurane anaesthesia 128.24+/-4.07, P<0.0014) th an in the control animals (12.22+/-1.52). Conclusion: Exposure to halo thane or isoflurane anaesthesia increased the number of pulmonary meta stases in C57Bl mice compared with the control groups but there was no difference in metastases among animals treated with halothane or isof lurane.