Expression of Topoisomerase II Alpha in Canine Colorectal Polyps, Adenomas and Adenocarcinomas.

With the development and increased accessibility of diagnostic methods in veterinary medicine, the possibilities for early detection of proliferative lesions in the canine large intestine have expanded over the past decade. Since in human medicine, topoisomerase II alpha (Topo IIα) is considered a prognostic and predictive marker in various tumours, including colorectal carcinoma, we aimed to verify the role of this enzyme in proliferative epithelial lesions of the canine large intestine. In this study, we examined and compared the expression of Topo IIα in normal rectal mucosa, hyperplastic polyps, adenomas, and adenocarcinomas of the large intestine in dogs. Each type of lesion included 20 cases, in which the expression of Topo IIα was evaluated using immunohistochemistry. The median percentage of Topo IIα positive cells was 29.4% (IQR 24.9-37.1) in polyps, 30.3% (IQR 24.6-34.1) in adenomas, 36% (IQR 26.2-42.0) in adenocarcinomas, and 7.8% (IQR 5.9-10.6) in normal intestinal mucosa. Statistical analysis using the Kruskal-Wallis test followed by Dunn's post hoc tests with Bonferroni correction revealed significantly higher Topo IIα expression in hyperplastic polyps (p = 0.013, r = 0.62), adenomas (p = 0.033, r = 0.57) and adenocarcinomas (p = 0.002, r = 0.73) compared with normal rectal mucosa, with large effect sizes. Our results may serve as a preliminary basis for the potential use of anthracyclines in the treatment of canine colorectal adenocarcinomas, as well as in multiple adenomas or polyps when surgical options are limited. This study presents new insights of Topo IIα expression in canine large intestine carcinogenesis and could provide a valuable foundation for further clinical research.