Probiotic supplementation attenuates the aggressiveness of chemically induced colorectal tumor in rats.

To evaluate the effect of a probiotic on the aggressiveness of a chemically induced colorectal tumor in rats. Twenty-five male Fisher 344 rats, 250 g, provided with feed and water ad libitum, were randomly divided into 5 groups (5 rats/group): GControl, no treatment; GTumor, tumor induction; GTumor+5FU, tumor induction, 5-Fluorouracil applied; GTumor+Prob, induction of the tumor, supplemented with probiotic; GTumor+5-FU+Prob, tumor induction, 5-Fluorouracil applied, supplemented with probiotic. For tumor induction 20 mg/kg of 1,2-dimethylhydrazine was applied intraperitoneally over 4 weeks, followed by an interval of 15 days, and then repeated for a further 4 weeks. Five weeks after the final dose of the carcinogen, treatment was initiated with 5-Fluorouracil (15 mg/kg, intraperitoneally/week) and a commercial probiotic (1 × 109 CFU, daily/gavage). Data were analyzed by One Way Variance Analysis and means compared by Dunnett's test. GraphPad Prism statistical software was used. The histopathological analyzes were evaluated by the chi-square test. A 5% type-I error was considered statistically significant. Compared with the GTumor, the GTumor+Prob (p < 0.0373) and GTumor+5-FU+Prob (p < 0.0003) demonstrated an attenuated effect on the aggressiveness of the colorectal tumor, with a reduction in the count of Aberrant Crypt foci; and a lower percentage of malignant neoplastic lesions in the GTumor+Prob (40% low grade tubular adenoma, 40% carcinoma in situ, 20% low grade adenocarcinoma) and GTumor+5-FU+Prob (40% low grade tubular adenoma and 60% carcinoma in situ). Probiotic supplementation has the potential to decrease the formation of aberrant crypts and ameliorate tumor malignancy, enhancing the antitumor effect of 5-Fluorouracil chemotherapy in colic segments.