Occult blood testing using the guaiac method (haemoccult-test) for detection of tumorous lesions induced with 1,2-dimethyl-hydrazine and acetoxymethyl-methyl-nitrosamine in rats.

Colon tumors were induced by 1,2-Dimethylhydrazine (DMH) and Acetoxymethyl-methyl-nitrosamine (AMMN) in male Sprague-Dawley rats. The usefulness of the Haemoccult-test (HT) was investigated for early detection of these chemically induced tumorous injuries. As a prescreening method HT was shown to be unsuitable for early detection of tumours under the conditions of the models used. The accuracy of HT in cases of advanced chemically induced tumors was explored in rats with known colonic tumors, diagnosed by rectoscopy and exploratory laparotomy. In animals with proven colonic tumors HT gave a positive result only in 63% of rats with AMMN-induced tumors and in 50% rats with DMH-induced cancers. Therefore, HT is thought to be an insensitive and thus unsuitable method for the detection of colonic cancer in rats.