Mucosal proliferation characteristics in ureterosigmoidostomy: Effect of calcium supplement

Ureterosigmoidostomy, frequently performed in children for urinary diversion, is a known premalignant condition. Dietary calcium supplements have been shown to normalize mucosal proliferative patterns in other human premalignant colonic conditions, which might decrease the risk of cancer. However, calcium supplementation has not been investigated in ureterosigmoidostomy. We used a rat model to study the effects of increased dietary calcium on the progression to carcinoma in ureterosigmoidostomy. Twenty-five Wister rats underwent ureterosigmoidostomy by anastomosis of bladder trigone and ureters to sigmoid, and were divided into two groups: group 1, regular diet (14); and group 2, calcium supplemented (2%) diet (11). All animals received the diet for 9 months. At death the anastomosis was weighed and examined histologically. In addition, ornithine decarboxylase (ODC), an enzyme involved in polyamine synthesis that becomes elevated in neoplastic and proliferative disorders, was determined at the anastomosis and 8 cm proximal (normal colon). All animals developed proliferative metaplastic polyposis at the anastomosis. Tumor weights were 2.6±1.1 g for group 1 and 4.8±1.2 g for group 2 (P<.05). The ODC levels were: group 1, normal colon 78.2±15.6 and tumor 321.3±58.8 (P<.002); and group 2, normal colon 425.8±65.4 and tumor 568.0±40.9 (P=NS). The difference between group 1 normal colon and group 2 normal colon was significant (P<.001), as was group 1 tumor and group 2 tumor (P<.02). These data show that dietary calcium supplementation in this ureterosigmoidostomy-carcinoma model stimulates cell proliferation (ODC levels) in normal colon, and causes significant increases in tumor size and tumor ODC levels at ureterosigmoidostomy sites. Calcium-supplemented diets should be used cautiously in children with ureterosigmoidostomy.