EXPERIMENTAL LUNG CANCER IN RABBITS INDUCED BY CHEMICAL CARCINOGENS

Abstract

For the purpose of inducing experimental lung cancer, either suspension of 3-methylcholanthrene in distilled water or a mixture of 3-methylcholanthrene and 4-nitroquinoline 1-oxide in rabbit plasma was infused into the lower bronchus of the rabbits. The latter was given in combination with subcutaneous injections of 4-nitroquinoline 1-oxide.
1) Five rabbits developed typical lung cancer accompanying metastases and/or invasion into tissues adjacent to the lung. Metastases and invasion were observed in two with squamous-cell carcinoma and one with undifferentiated cell carcinoma. In the fourth one, the lesions were composed of the feature of squamous-cell carcinoma in some areas and of adenocarcinoma in other areas, and were seen to infiltrate into the diaphragm. The remaining one showed characteristics of adenocarcinoma with invasion into the diaphragmatic pleura. All of these rabbits received 16 to 41 applications of carcinogens over an experimental period of 127 to 397 days.
2) Twelve out of 32 rabbits having received more than 4 infusions and survived 30 days or more developed adenocarcinoma not accompanied with metastasis and invasion into the adjacent tissues.
3) Discussion were made with regard to the sites of the application and vehicles used for the carcinogens.