ABSTRACT

In experimental lung carcinogenesis studies, systemic administration of carcinogens, including intravenous (IV) injection, has been used ever since this type of experiment first appeared in the literature. In association with the frequent occurrence of lung metastases and demonstration of lung tumors by IV injection of tumor cell suspension, IV administration of chemical carcinogens has attracted much attention in experimental lung carcinogenesis. Although N-nitroso compounds have been examined systematically, the number of lung carcinogenicity studies using IV administration is limited. In N-nitroso carcinogenesis, some studies using IV administration have contributed to a clearer understanding of the mechanism of carcinogenesis. Many studies have demonstrated frequent uptake of tumor cells in the lung of various species following IV administration of tumor cell suspension. However, there are such large differences in size and plysicochemical properties that tumor cells and chemical carcinogens may not be directly comparable in their behavior.