EFFECTS OF SELENIUM ON GALLBLADDER CARCINOGENESIS INDUCED BY AN INTRACHOLECYSTIC 3-METHYLCHOLANTHRENE BEESWAX PELLET IN FEMALE SYRIAN GOLDEN-HAMSTERS

This study represents the first report of the effects of selenium (Se) on chemically induced gallbladder carcinogenesis in hamsters. A total of 100 female Syrian golden hamsters was randomly assigned to four gr oups, which groups of 25 hamsters were given ad libitum drinking water containing either 0.0, 0.5, 2.0 or 4.0 ppm Se (as sodium selenite) fo r 24 weeks. Initiation was performed at week 4 by the insertion of a B eeswax pellet containing 3-methylcholanthrene (3-MC) into the gallblad der. The incidence of total malignant tumors at the end of the study ( 24 weeks) was 88, 75, 81 and 82% in the 0.0, 0.5, 2.0 and 4.0 ppm Se g roups, respectively. All the cases of carcinoma but two were considere d to develop through the sequence from dysplasia to carcinoma in situ (CIS) and from CIS to adenocarcinoma of invasive type, The incidence o f CIS was significantly lower in hamsters treated without Se than in t hose treated with Se (P < 0.05). On the other hand, the incidence of i nvasive adenocarcinoma was significantly higher in the former than in the latter (P < 0.05). These results were summarized that Se might ret ard the progression of hamster gallbladder carcinogenesis induced by a 3-MC beeswax pellet.