Abstract :
[en] BACKGROUND. Metallothioneins (MT) are low-molecular weight, metal-binding
proteins that play a role in cellular proliferation and differentiation, as well as in
cellular defense mechanisms. They act as scavengers of free radicals produced by
irradiation. A number of in vitro and in vivo studies have linked overexpression of
cellular MT with tumor cell resistance to radiation. This is the first study that
investigates whether MT expression is involved in the radioresistance of rectal
carcinoma.
METHODS. Using a mouse monoclonal antibody, MT expression was analyzed by
immunohistochemistry on surgical samples (n 85) from 85 patients with locally
advanced rectal carcinoma who were treated preoperatively with a hyperfractionated
and accelerated radiotherapy schedule and on tumor biopsies (n 13)
obtained before treatment. The potential correlations between MT expression and
pathologic variables and survival were examined.
RESULTS. MT were expressed strongly in both the cytoplasm and nucleus of tumor
cells in 7 biopsy and 42 surgical samples. A comparison of MT expression in biopsy
and surgical specimens showed that MT expression did not change after irradiation
in most cases. Against all expectations, MT were expressed more frequently in
tumors from responders than in those from the nonresponders (P 0.02). There
was no correlation between MT expression and tumor stage, histology after radiotherapy,
or survival.
CONCLUSION. These findings do not support the hypothesis that MT overexpression
at the end of radiotherapy is a marker for radiation resistance. Cancer 2002;95:
1003–8. © 2002 American Cancer Society.
DOI 10.1002/cncr.10780
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