Df. Hargreaves et al., EPITHELIAL PROLIFERATION AND HORMONE-RECEPTOR STATUS IN THE NORMAL POST MENOPAUSAL BREAST AND THE EFFECTS OF HORMONE REPLACEMENT THERAPY, British Journal of Cancer, 78(7), 1998, pp. 945-949
The proliferation rate las assessed by Ki67 expression) and expression
of oestrogen-regulated progesterone receptor (PR) was studied in norm
al post-menopausal breast epithelium. Normal breast epithelium from pa
tients receiving hormone replacement therapy (HRT) at the time of surg
ery containing either oestrogen alone (E-2) or oestrogen and progester
one combined activities (E-2 + P) was also studied, as HRT has been li
nked to an increased breast cancer risk. Samples of breast tissue, con
taining normal epithelium, from 185 patients undergoing surgery for be
nign or malignant disease were immunocytochemically stained for PR and
Ki67. The percentage of labelled cells was expressed as the labelling
index (LI). The median Ki67 LI in normal post-menopausal breast epith
elium was 0.19 and median PR LI was 4.75, and both were unaffected by
patient age, duration of menopause or if the tissue sample originated
from a breast with benign or malignant disease. Proliferation did not
alter significantly in patients taking HRT (P = 0.61); however, PR exp
ression was up-regulated in both E-2 and E-2 + P users (P = 0.01). The
dose and duration of HRT had no effect on either parameter. A possibl
e attenuation of sensitivity to oestradiol-induced proliferation but n
ot to PR expression occurs in the post-menopausal breast.