Late effects of intraoperative radiation therapy in anastomotic rat colon.
OBJECTIVE
to determine whether intraoperative radiotherapy causes long-term negative effects on the healing of colonic anastomoses in the rat.


METHODS
175 rats were divided into seven equal groups. One group served as sham-irradiated control group. In the others, following a colonic resection, 1 or 2 cm of the distal bowel limb was irradiated with a single dose of 10, 15, or 20 Gy (groups 10/1, 15/1, 20/1, 10/2, 15/2, and 20/2, respectively). Subsequently, an anastomosis was constructed. The animals were killed after 6 (n = 10 in each group) or 12 (n = 15) months. The abdomen was inspected for abnormalities and the colonic diameter was measured. The anastomotic segment was analyzed biochemically (hydroxyproline) and histologically.


RESULTS
During the experimental period, 1 rat (group 15/1) died because of anastomotic leakage and 3 others died from unknown causes. There was no difference in colonic diameter between groups. Altogether 17 rats developed an adenocarcinoma in the irradiated area: 11 of these had received a dose of 20 Gy. Histological observation indicated that fibrosis was present only in a limited number of animals, mostly after irradiation with a dose of 15 or 20 Gy. All anastomoses were functional and showed normal histology. The hydroxyproline content of the anastomotic segment was increased--with respect to the control group--only in the 20/2 group after 6 months. After 12 months, the hydroxyproline concentration in the (irradiated) segment distal to the anastomosis proper was higher in the 10/1 and 15/1 groups than in the control group. Otherwise, there were no differences between groups.


CONCLUSIONS
Intraoperative irradiation with a single dose of 10-20 Gy, delivered to the distal limb used for anastomotic construction, does not appear to constitute a threat to anastomotic integrity. Dose-related changes included formation of adenocarcinomas and fibrosis, but function and histology of the anastomosis proper remained unaffected.
Seifert
W F
WF
Department of Surgery, University Hospital Nijmegen, The Netherlands.
Biert
J
J
Wobbes
T
T
Verhofstad
A A
AA
Hoogenhout
J
J
Hendriks
T
T
D000714:Anastomosis, Surgical; D000818:Animals; D015415:Biomarkers; D003106:Colon / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects* / Q000601:surgery; D006909:Hydroxyproline / Q000378:metabolism; D007432:Intraoperative Period; D008297:Male; D011183:Postoperative Complications / Q000378:metabolism / Q000473:pathology; D011829:Radiation Dosage; D011833:Radiation Injuries, Experimental / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D014945:Wound Healing / Q000528:radiation effects*
D015415:Biomarkers; D006909:Hydroxyproline