Colonic perianastomotic carcinogenesis in an experimental model

Forty-three 10-week-old male and female Sprague-Dawley rats were operated on by performing an end-to-side ileorectostomy. Group A:16 rats received no treatment. Group B: 27 rats received 18 subcutaneous injections weekly at a dose of 21 mg/kg wt of 1–2 dimethylhydrazine (DMH), from the eighth day after the intervention. Animals were sacrificed between 25–27 weeks. The number of tumours, their localization, size and microscopic characteristics were recorded. A paired chi-squared analysis was performed comparing tumoral induction in the perianastomotic zone with the rest of colon with faeces.No tumours appeared in the dimethylhydrazine-free group. The percentage tumoral area was greater in the perianastomotic zone compared to tumours which had developed in the rest of colon with faeces (p = 0.014).We found a cocarcinogenic effect due to the creation of an anastomosis, when using an experimental model of colonic carcinogenesis induced by DMH in rats.Colorectal cancer (CRC) is a frequent tumour, with an elevated mortality in western countries [1]. It is the second cancer in the population of Asturias (Northern Spain), and represents 13% of the total number of cases of cancer diagnosed annually. CRC causes 3.7% of the total number of deaths and 14.1% of the deaths due to cancer [2].To study the influence of the different etiological environmental factors on colon cancer in man, long-term prospective studies are difficult to carry out [3].Several authors have suggested that colon cancer is promoted by non-specific colonic lesions [4,5]. Late anastomotic recurrences of colorectal carcinoma could be explained by this hypothesis [6-9].The induction of colorectal cancer with 1–2 dimethylhydrazine (DMH) in rats is a currently valid experimental model, which is transferable to humans, both in their macro-microscopic and biological behaviour [10-12].The aim of the present study was to investigate the effect of anastomosis in the colon of rats subjected to colonic tumoral inducti