The effects of diet and ionizing radiation on azoxymethane induced colon carcinogenesis

The ability of ionizing radiation to enhance colon carcinogenesis and the role of diet in this process has not been documented. We hypothesized that radiation would enhance the formation of aberrant crypt foci, ACF, known precursor lesions to colon cancer, by suppressing apoptosis and upregulating proliferation in colonocytes. Diets contained a combination of fish oil or corn oil and either pectin or cellulose. We exposed 40 male Sprague-Dawley rats to 1 Gy ionizing radiation (1 GeV Fe) 10 d prior to injection with AOM. Colons were resected at the promotion stage of carcinogenesis (7 wk post initial injection) and assayed for ACF and apoptosis. Radiation treatment increased (P=0.0327) the incidence of high multiplicity ACF (foci with four or more aberrant crypts) and decreased (P=0.0340) the apoptotic index compared to non-irradiated rats. Radiation also resulted in an increase (P