A SEMIQUANTITATIVE HISTOLOGICAL ANALYSIS OF REPAIR OF ANASTOMOSES IN THE RAT COLON AFTER COMBINED PREOPERATIVE IRRADIATION AND LOCAL HYPERTHERMIA

Hyperthermia is a promising method for increasing the efficacy of radi ation therapy of colorectal cancer. To study the histological aspects of healing of an anastomosis in the colon, after combined preoperative (sham) irradiation and (sham) hyperthermia treatment, 48 male Wistar rats were divided randomly into four groups. In each animal, a segment of the colon was treated successively by (sham) irradiation (single d ose of 25 Gy X rays) and/or (sham) hyperthermia (44 degrees C, 30 min) . After 5 days, a resection of the colon was performed by construction of an anastomosis: The distal limb consisted of (sham-) irradiated an d/or (sham-) hyperthermia-treated bowel. Rats were killed 3 or 7 days after the surgical procedure. Evaluation of healing of the anastomosis was made by: (1) histological analysis of sections stained with hemat oxylin and eosin, (2) semiquantitative measurement of collagen in the area of the anastomosis and (3) semiquantitative analysis of the numbe r of macrophages by immunocytochemistry. Healing of the anastomoses in animals receiving irradiation or hyperthermia alone and in control an imals was relatively uneventful. There were no differences between gro ups in formation of collagen or infiltration by macrophages in the are a of the anastomosis. Animals treated with both radiation and hyperthe rmia showed marked necrosis, infiltration by polymorphonuclear leukocy tes and rupture of the anastomosis. It is concluded that preoperative irradiation with a single dose of 25 Gy in combination with local hype rthermia at 44 degrees C for 30 min leads to disturbed repair of anast omoses. (C) 1998 by Radiation Research Society.