Early X-ray detection of colonic and rectal tumours in European hamsters.

Three groups of European hamster (EH) (Cricetus cricetus L.) were treated subcutaneously every two weeks for life with 1/10 or 1/20 LD50 DMH, while two other groups served as controls. Twelve weeks after commencement of treatment, radiological examinations of the colon and rectum were begun. The double contrast method was used. In this way it was possible to detect the earliest neoplastic alteration to take place in the above sites. This occurred in the 26th treatment week and was diagnosed as an adenocarcinoma. The technique used is simple, as well as being suitable for large numbers of animals. In addition, it allows for early experimental analysis of results in respect to latency period, growth rate, incidence and location of tumours.