Effect of HZE radiation and diets rich in fiber and n-3 poly unsaturated fatty acids (n-3 PUFA) on colon cancer in rats

This study examines the carcinogenic effect of HZE radiation and protective effects of different types of diets against colon carcinogenesis in a rat model. The effect of HZE radiation on health state and colon cancer development was evaluated. HZE radiation was found to suppress food consumption (P<0.0001) leading to lower body weight gain of irradiated rats when compared to the non-irradiated rats (P<0.05). The animals exposed to HZE radiation were found to start dying and/or getting pathologies 11 weeks earlier and at the end of the study had morbidity/mortality rate 14.2% higher (P=0.0005) than non-irradiated rats. There was no significant effect of HZE radiation on colon cancer incidence. The effects of dietary fibers and oils on health state and colon carcinogenesis were evaluated. Morbidity/mortality was found to be delayed in rats fed with pectinbased diets when compared to cellulose-based diet, regardless of radiation treatment. Similarly, fish oil was found to beneficially affect health of the experimental animals when compared to corn oil. Ten- and twenty-week delayed morbidity/mortality for irradiated and non-irradiated groups, respectively, was observed for rats fed with fish oil-based diets when compared to corn oil-based diets. Fish oil was also found to significantly reduce colon tumor incidence and multiplicity in non-irradiated rats (P<0.05). A similar trend was observed for the irradiated animals. No significant effect of fiber on colon cancer incidence was found. Finally, the effect of diets on general health and colon cancer development was investigated. Rats fed with corn oil/cellulose diet started dying and/or getting a disease earlier than rats fed with other diets, regardless of radiation treatment. The effect of diet on colon cancer development was found to depend on radiation treatment. Thus, in the absence of radiation treatment fish oil/cellulose was found to significantly reduce tumor incidence and multiplicity when compared to corn oil/pectin diet (P<0.05). In the presence of radiation treatment fish oil/pectin was found to lower the values of tumor incidence and tumor multiplicity, though the data obtained were not significant.