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 carcinogeaesis in hamsters. A total of 100 female Syrian golden hamsters was randomly assigned to four groups, 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) for 24 weeks. Initiation was performed at week 4 by the insertion of a Beeswax pellet containing 3-methylcholanthrene (3-MC) into the gall-bladder. 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 groups, respectively. All the cases of carcinoma but two were considered to develop through the sequence from dysplasia to carcinoma in situ (CIS) and from CIS to adenocarcinoma of invasive type. The incidence of CIS was significantly lower in hamsters treated without Se than in those treated with Se (P < 0.05). On the other hand, the incidence of invasive adenocarcinoma was significantly higher in the former than in the latter (P < 0.05). These results were summarized that Se might retard the progression of hamster gallbladder carcinogenesis induced by a 3-MC beeswax pellet.