One tantalizing mystery about the pathogenesis of large-bowel neoplasms is that, while common in man, these tumors have rarely been observed to arise spontaneously in laboratory animals. Moreover, the induction of colon tumors by known experimental means has been accomplished infrequently.1 At the present time, the data these few successful experiments do not seem applicable to human material.
It was, therefore, with considerable interest that some two years ago we first observed, previously unrecorded, adenomatous polyps and adenocarcinomas of the large intestine in the Syrian hamster.2,3 Our interest was further heightened by the similarity of these hamster tumors to comparable human tumors and by the great frequency with which they were observed.
Materials and Methods
The experiment was initiated during the period of December, 1954, to April, 1955. Six hundred twenty weanling Syrian hamsters were obtained from a commercial dealer and, after stabilization 1 the laboratory, were separated into various