Environmental temperature and metastatic spread of melanoma in the crested newt

The influence of environmental temperature on tumor growth in newts injected subcutaneously with melanoma cell suspensions was studied. No signs of tumor growth were observed in animals kept at 4 degrees C, even after 1 year, whereas animals kept at 30 degrees C died after 2-4 weeks of widespread metastatic disease. In newts kept at both 17 degrees C and 27 degrees C and killed 25 days after the tumor grafting, blood-borne tumor emboli were often found. However, widespread metastases were present only in those kept at 27 degrees C. These findings suggest that by operating at a proper environmental temperature to slow down tumor growth, melanoma of the crested newt could serve as a useful experimental model for study of the different steps of metastatic spread.