Spontaneous tumors in C3H-A vy and C3H-A vy fB mice: high incidence in the United States and low incidence in Australia.

Abstract

C3H-Avyy and C3H-Avy, fB mice, with a virtual 100% incidence of liver and mammary tumors in the United States, had an almost 0% incidence of these tumors when these mice were bred and reared in Australia, particularly after the first generation. C3H-Avymice, when reared in Australia but provided with U.S. feed and bedding (cedar shavings), also had essentially a 100% incidence of mammary tumors. Although our results did not rule out other possibilities, the implication of cedar as a carcinogenic” agent was quite clear-cut. These observations, although not yet made on large numbers of mice, provide new parameters for the study and understanding of the development of spontaneous mammary and liver cancer in mice.â€J Natl Cancer Inst 50: 1237-1242, 1973. © 1973 OUP Publishing Ltd.