W. D. George

Anastomotic suture materials and experimental colorectal carcinogenesis

Local tumor recurrence following restorative surgery for colorectal cancer may occasionally result from the promotion of a neoplastic lesion in a zone of proliferative instability adjacent to the anastomosis. The aim of this study was to compare the influence of three anastomotic suture materials, including stainless steel (as a model of surgical stapling), on colorectal carcinogenesis in an experimental animal model. The transmural implantation of stainless steel sutures into the distal descending colon of albino Swiss rats during the postinitiation phase of tumor induction resulted in significantly fewer animals exhibiting perianastomotic tumors 12 weeks later (3 of 21 animals) when compared with either polyamide (Nurolon®; Ethicon, Edinburgh, United Kingdom) (14 of 20 animals;P<0.001) or polyglycolic acid (Dexon Plus®; Davis and Geck, Gosport, United Kingdom) sutures (17 of 21 animals;P <0.001). The findings were similar when the same materials were used to resuture a longitudinal colotomy. For both operative procedures, the type of suture material had no influence on the incidence of large bowel tumors distant from the anastomotic site. These results suggest that stainless steel staples may promote fewer perianastomotic large bowel tumors than certain more conventional suture materials and, therefore, may be safely employed in colorectal cancer surgery.

Dietary manipulation during experimental colorectal carcinogenesis: A morphological study in the rat

The effect of the dietary manipulation of fat and fibre on the gross pathological, histopathological and scanning electron microscopic appearances of colonic mucosa was studied before and during experimental carcinogenesis in 232 male Albino Swiss rats. Carcinogen treated animals were given 12 consecutive weekly injections of Azoxymethane in a dose of 10 mg/kg per week. The animals were divided between four dietary groups (1: high fat high fibre, 2: low fat high fibre, 3: high fat low fibre and 4: low fat low fibre). The colorectal morphology was assessed at autopsy using standard histopathological techniques. In addition, scanning electron microscopic studies on selected samples were performed. A scoring system was introduced to allow a more accurate comparison of the surface architectural appearances. The high fat low fibre diet was associated with the greatest risk for macroscopic tumour production and the low fat high fibre diet with the lowest risk. Statistically significant differences between each of the dietary groups were noted with the exception of the comparison for tumour induction between the high fat high fibre and low fat high fibre dietary groups. Histopathological analysis confirmed the inter dietary relationships with respect to the extent of neoplastic change. The scanning electron microscopic study revealed that both dietary manipulation and carcinogen treatment influenced the surface characteristics. Control animals fed diet 2 (low fat high fibre) but not treated with carcinogen, showed the greatest deviation from the normal appearances. Animals treated with carcinogen and fed diet 3 (high fat low fibre) consistently showed the greatest surface abnormalities.