Effects of two conventional preoperative radiation schedules on anastomotic healing in the rat colon.
BACKGROUND
Preoperative radiotherapy (RT) is an increasingly popular form of adjunct therapy for rectal cancer; however, little is known about its effects on matrix metalloproteinase (MMP) expression in colonic anastomotic healing.


METHODS
Wistar rats were irradiated to a total dose of 25 or 40 Gy. Four days after the end of RT, an end-to-end colorectal anastomosis was performed. Animals were sacrificed at 1, 3, and 7 days after the anastomosis. A control group was studied similarly, but was not irradiated.


RESULTS
No significant differences were found in peritonitis rate and anastomotic complications. The average bursting pressure and breaking strength were only reduced significantly in the rats irradiated with 40 Gy. However, the concentration and the content of hydroxyproline in anastomotic tissues were unchanged. In irradiated rats, MMP-2 and MMP-9 were significantly increased at 40 Gy, but not at 25 Gy. On the other hand, 25-Gy irradiation induced a smaller increase in the levels of the tissue inhibitors of metalloproteinase-1 compared with the controls.


CONCLUSIONS
Anastomotic strength is adversely affected by high-dose fractionated preoperative RT. In contrast, preoperative RT at 25 Gy in five fractions over 5 days is safe with regard to the maintenance of wound strength in colorectal anastomosis.
Bedirli
Abdulkadir
A
Department of General Surgery, Gazi University Medical School, Ankara, Turkey. bedirlia@gazi.edu.tr
Kerem
Mustafa
M
Karahacioglu
Eray
E
Ofluoglu
Ebru
E
Yilmaz
T Utku
TU
Pasaoglu
Hatice
H
Tater
O Petek
OP
Sakrak
Omer
O
Pak
Yucel
Y
D000714:Anastomosis, Surgical; D000818:Animals; D001696:Biomechanical Phenomena; D003106:Colon / Q000601:surgery*; D006909:Hydroxyproline / Q000528:radiation effects; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000528:radiation effects*; D020780:Matrix Metalloproteinase 9 / Q000528:radiation effects*; D011300:Preoperative Care; D011879:Radiotherapy Dosage; D018714:Radiotherapy, Adjuvant / Q000379:methods; D051381:Rats; D017208:Rats, Wistar; D012004:Rectal Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000528:radiation effects; D014945:Wound Healing / Q000528:radiation effects*
D019715:Tissue Inhibitor of Metalloproteinase-1; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D006909:Hydroxyproline