Effect of iodoacetamide or Tween 60 on methylnitrosocyanamide carcinogenesis in rat glandular and forestomach.

The effect of iodoacetamide or Tween 60 on carcinogenicity of methylnitrosocyanamide (MNC) in rats was examined. A significant increase in the incidence of the forestomach tumors (P less than 0.01) was observed in rats treated with MNC and iodoacetamide simultaneously. Moreover, there were 2 cases of glandular stomach tumors in rats treated with MNC and Tween 60 simultaneously. They were one well-differentiated adenocarcinoma and one polypoid hyperplasia. This result indicates that MNC under certain conditions is carcinogenic to the glandular stomach of rats in addition to the forestomach. Tween 60 might act by facilitating direct contact between MNC and the glandular stomach mucosa.