Effect of combined tigason and selenium treatment on colon carcinogenesis.

The modifying effect of an aromatic retinoic acid analog. Tigason, alone or in a combined regimen with selenium on the incidence of colon tumors induced by 1,2-dimethylhydrazine was investigated in BD rats. Treatment with the carcinogen alone resulted in induction of colon adenocarcinomas in 29 rats (92%). In comparison to the 1,2-dimethylhydrazine-treated group, administration of Tigason or Tigason plus selenium reduced tumor incidence (71% and 68%, respectively). The effect of combined treatment with Tigason and selenium, however, was not additive. Although some researchers have been unable to demonstrate any protective effect of different synthetic retinoids against 1,2-dimethylhydrazine or N-methyl-N-nitrosourea-induced colon tumors, our findings suggest that the process of tumor initiation in colon mucosa can be significantly influenced by the aromatic retinoid Tigason or by simultaneous administration of Tigason and selenium.