The Effect of Yeast Feeding upon Experimentally Produced Liver Cancer and Cirrhosis

o-Aminoazotoluene (2~) and p-dimethylaminoazobenzene (6) are equally effective when given orally in producing liver cancer in rats. This change occurs after 3oo days when o-aminoazotoluene is used and after only i5o days with p-dimethylaminoazobenzene. In some instances, however, liver cancers are produced by either substance at earlier time intervals. The sequence of events is not the same with both dyes. When p-dimethylaminoazobenzene is used, the usual sequence is first the formation of cirrhosis which is generally manifest at the end of 60 days. As a rule, by 9 ~ days most of the livers show cholangiomas and at this time some hepatomas are also present. Then, as time goes on, the production of hepatomas increases. Ordinarily by the I5oth day practically all the livers are the seat of a cancerous process (both cholangiomas and hepatomas). Wi th o-aminoazotoluene the first pathological alteration is usually a hepatoma formation or occasionally the development of cholangioma. Cirrhosis generally does not develop and if it does is usually not pronounced. The malignant transformation of the liver cells to hepatomas occurs more slowly with o-aminoazotoluene than with p-dimethylaminoazobenzene and takes place in about 3o0 days.