Purpose: To investigate the incidence of tumour metastasis from B16 melanoma tumour cells in experimental animals following exposure to equipotent concentrations of halothane or isoflurane, and to differentiate if exposure to one anaesthetic resulted in greater metastases than the other.
Methods: Experimental animals (C57B1 mice), were randomized to receive 1.3 MAC hours of halothane or isoflurane anaesthesia. The control group of animals received oxygen alone under identical conditions. Fifteen minutes after completion of anaesthesia, control and experimental groups were given 1 x 10(5) B16 melanoma cells intravenously. After 21 days, all animals were autopsied, and the metastatic nodules in their lungs were counted. The difference in the numbers of metastatic nodules between control and experimental groups of animals was analyzed for significance by the Mann Whitney "U test".
Results: More metastases were observed in the animals exposed to halothane (37.28 +/- 5.08, P < 0.0001), or isoflurane anaesthesia (28.24 +/- 4.07, P < 0.0014) than in the control animals (12.22 +/- 1.52).
Conclusion: Exposure to halothane or isoflurane anaesthesia increased the number of pulmonary metastases in C57B1 mice compared with the control groups but there was no difference in metastases among animals treated with halothane or isoflurane.