HIGH-DOSE PREOPERATIVE IRRADIATION WITHOUT DETRIMENTAL EFFECT ON EARLY REPAIR OF ANASTOMOSES IN THE COLON OF THE RAT

Preoperative radiotherapy as an adjunct to surgery for rectal carcinom a is generally thought to impair the healing of colorectal anastomoses . To delineate the presumed hazards of preoperative irradiation, we in vestigated this effect in a new model where, in contrast to experiment s reported so far, anastomoses were constructed using normal tissue fo r the proximal limb and irradiated tissue for the distal limb. A group of 120 male Wistar rats, divided randomly into 12 groups of 10 each, were used. In 60 animals, a colonic segment of 2.2 cm was irradiated w ith a single dose of 25 Gp X rays administered 28 or 5 days or 3 or 1 day(s) before colonic resection. For each experimental group, a contro l group was included which was sham-irradiated on the same preoperativ e day. The animals were sacrificed on the third or the seventh postope rative day, and healing of the anastomosis was evaluated by measuremen t of bursting pressure, breaking strength and hydroxyproline concentra tion and content. Comparison between each experimental group and its c ontrol group showed that preoperative irradiation did not reduce the s trength of the anastomoses. Also, the concentration and content of hyd roxyproline in the tissue of the anastomoses were unchanged. These dat a indicate that construction of a colonic anastomosis consisting of on e irradiated bowel end in rats is not by definition detrimental to the development of early Wound strength. (C) 1997 by Radiation Research S ociety.