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 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 gallbladder. 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.

Distribution of selenium and molybdenum and cancer mortality in Niigata, Japan.

Selenium and molybdenum have inhibitory effects on gastrointestinal carcinogenesis. We investigated the levels of selenium and molybdenum in sediments and mortality from cancers at specific sites in 19 areas of Niigata Prefecture, Japan, and compared these factors. The average concentrations of selenium and molybdenum were 0.44 +/- 0.19 ppm (micrograms/g dry weight; mean +/- standard deviation) and 3.82 +/- 1.03 ppm, respectively. Selenium was not associated significantly with cancer mortality. There were inverse correlations between molybdenum levels and female mortality from cancers of the esophagus (r = -.446, .05 < p < .1) and rectum (r = -.529, p < .05). Molybdenum was correlated positively with female mortality from cancer of the pancreas (r = .603, p < .01). Further investigations are needed for causal interpretation of these results.

Selenium contents in human gallbladder bile.

The selenium contents in human gallbladder bile were analyzed. Thirty-seven subjects were studied; 22 patients with cholelithiasis in Niigata Prefecture and 15 patients (13 with cholelithiasis and 2 with gallbladder polypus) in Kochi Prefecture. Five ml of bile was withdrawn with a syringe from the gallbladder during the operation and stored at -20 degrees C until analysis. For the analysis by gas chromatograph with an electron-capture detector, 0.2 ml of sample was used. The mean selenium contents in bile were 269 +/- 39.0 (mean +/- S.D.) ng/ml for the subjects in Niigata and 285 +/- 84.4 ng/ml in Kochi; without significant difference. Of 37 samples analyzed, the mean content was 276 +/- 61.0 ng/ml.