Microsomal epoxide hydrolase expression as a predictor of tamoxifen response in primary breast cancer: A retrospective exploratory study with long-term follow-up
P. Fritz et al., Microsomal epoxide hydrolase expression as a predictor of tamoxifen response in primary breast cancer: A retrospective exploratory study with long-term follow-up, J CL ONCOL, 19(1), 2001, pp. 3-9
Purpose: It has been suggested that estrogen receptor-independent high-affi
nity binding sites for antiestrogens could limit their local bioavailabilit
y and response. Microsomal epoxide hydrolase (mEH) was recently shown to be
ct component of the antiestrogen binding site complex. We investigated whe
ther mEH expression in primary breast tumors is related to disease outcome
and to the efficacy of tamoxifen treatment.
Patients and Methods: Expression of mEH was semiquantitatively assessed by
immunohistochemistry in sections prepared from archival paraffin blocks of
primary breast cancers from 179 patients with a mean follow-up time of 81 m
onths.
Results: Expression of mEH was correlated with poor disease outcome in ail
patients (P < .01; n = 179) and in patients receiving tamoxifen (P < .01; n
= 78), but not in patients not treated with tamoxifen. Moreover, mEH was a
n independent prognostic factor by Cox regression analysis.
Conclusion: The results of this first exploratory study suggest that mEH ex
pression in primary breast cancer could be of predictive value for response
to tamoxifen treatment and/or may be a novel independent prognostic factor
for survival. The results are in agreement with the model that mEH partici
pates in an estrogen receptor-independent tamoxifen-binding complex. J Clin
Oncol 19:3-9. (C) 2001 by American Society of Clinical Oncology.