THE INFLUENCE OF THE INTERACTION OF SUTURES WITH THE MUCOSA ON TUMOR-FORMATION AT COLONIC ANASTOMOSES IN RATS

In order to explore the respective role of wound healing and suture ma terial on metachronous carcinogenesis at colonic lines in rats, tumour yield was studied after the administration of a chemical carcinogen ( azoxymethane) at the moment that in one group of rats most of the sutu re material was still present and crypt cell proliferation elevated, w hile in another group, no more suture material was present and crypt c ell proliferation rate (CCPR) normalized at the anastomotic site. Azox ymethane (15 mg/kg/week, s.c., during 6 weeks) was administered in mal e Sprague-Dawley rats (n = 105) 8 weeks after the creation of an anast omosis in the ascending and descending colon with either stainless ste el sutures (group A, n = 30) or fast-absorption Vicryl (Vicryl Rapide( R), group B, n = 30). A control group (group C, n = 30) underwent a sh am laparotomy before the administration of azoxymethane, while the ani mals of a fourth group (group D, n = 15) were not operated upon and re ceived no azoxymethane. Twenty-six weeks after the first injection of azoxymethane there was no significant difference in the total colorect al tumour yield in the three operated groups (A, B, C), but a signific antly greater proportion of anastomotic tumours (28/68 vs. 13/68, p < 0.01) and more anastomotic tumours per rat (28/23 vs. 13/28, p = 0.01) as well as more rats with anastomotic tumours (16/23 vs. 11/28, p = 0 .04) were found in the steel-sutured group (A), compared with the cont rol group (C). No significant differences were observed in tumour dist ribution between the groups in which the anastomoses were carried out with Vicryl Rapide (B) and the control group (C). Thirty-six weeks aft er operation steel sutures were recovered in 30.4% (7/23) of the left- sided anastomoses and in only 8.7% (2/23) of the right-sided anastomos es. At that time, CCPR was significantly elevated in the left-sided an astomoses only, while the CCPR in the right-sided anastomoses was norm al when compared with all the other groups (A, B, C and D). The presen t study showed a shift in the distribution of tumours towards the anas tomotic sites at which suture material was present and the CCPR raised , at the moment of carcinogen administration, confirming the importanc e of the interaction of sutures with the mucosa in tumour formation. T he actual elimination process of the suture material might influence t he CCPR and act as a cocarcinogenic factor. In view of these observati ons, either the use of strictly inert suture material or the developme nt of sutureless anastomotic techniques should be encouraged in the co nstruction of colonic anastomoses.