by Gervaz P, Hennig R, Buechler M, Soravia C, Brigstock DR, Morel P, Egger JF, Friess H.
There is accumulating evidence, both quantitative and qualitative, that pelvic irradiation affects anorectal function. However, the molecular mechanisms responsible for radiation-induced damage to the anal sphincter remain unclear. AIM: To determine the expression of transforming growth factor-beta 1 (TGF-beta 1) and its downstream effector connective tissue growth factor (CTGF) in the anal sphincter of a patient irradiated for prostate cancer.
A 82 year-old patient developed a rectal adenocarcinoma and underwent an abdomino-perineal resection (APR), four years after receiving pelvic irradiation for prostate carcinoma.
Tissue sections of the anal sphincter were processed for histology. Immunostaining for TGF-beta 1 and CTGF were performed. RESULTS: CTGF and TGF-beta 1 immunoreactivity was detected in the irradiated anal sphincter, and was absent in controls. Immunoreactivity for both cytokines predominated in the internal sphincter. CTGF and TGF-beta 1 were preferentially detected in endothelial cells, myofibroblasts and fibroblasts; in addition, there was strong immunoreactivity for TGF-beta 1, but not for CTGF in smooth muscle cells of the anal canal.
Four years after pelvic irradiation, radiation-induced damage appeared to affect predominantly the smooth muscle layer of the anal canal. The molecular mechanisms responsible for radiation-induced fibrosis to these tissues involve prolonged activation of TGF-beta 1 and its downstream effector CTGF.
in Swiss surgery, Schweizer Chirurgie, Chirurgie suisse, Chirurgia svizzera 2003; 9(4): 193-7