Inositol hexaphosphate inhibits large intestinal cancer in F344 rats 5 months after induction by azoxymethane.

A treatment regimen of 2% Na-InsP6 in drinking water was effective in significantly reducing large intestinal cancer in F344 rats even when the treatment was begun 5 months after carcinogenic induction with azoxymethane (AOM 8 mg/kg/wk X 6). Compared to untreated (AOM-only) rats, animals on InsP6 had 27% fewer tumors (P less than 0.02). The tumors were approximately two-thirds smaller in size (P less than 0.01) and percentage mitotic rate in the non-neoplastic epithelium was less than half (1.0 +/- 0.1, compared to 2.3 +/- 0.2 of AOM-only animals, significant at P less than 0.001). We postulate that InsP6 may exert its antineoplastic effect by way of regulating cellular proliferation even after effective carcinogenic stimuli and thus may be an important candidate for chemointervention.