Estrogen receptor alpha and beta profiling in human breast cancer.
BACKGROUND
The identification of a second estrogen receptor (ER-beta) has significant implications for therapeutic strategy in breast cancer management arising from the potential agonist effect of Tamoxifen at estrogen receptor sites and as such, antiestrogen therapy may be inappropriate in patients with a dominance of ER-beta.


METHODS
To determine the proportion of breast cancer patients who may be so at risk, we developed a novel multiplexed RT-PCR technique to establish the relative ER-alpha and ER-beta levels in 53 primary breast cancers, 11 normal breast tissues and six cell lines. We further assessed the prognostic significance of receptor status relative to the Nottingham prognostic index (NPI). The ER-alpha and ER-beta status was also determined by immunohistochemistry using previously published and 'in-house' scoring systems.


RESULTS
Using RT-PCR analysis, 46 tumours were hormone receptor positive (ER+) with 42 displaying ER-alpha predominance. Comparison with immunohistochemistry demonstrated 44/53 (ER-alpha) and 27/50 (ER-beta) concordance rates. There was no significant difference in the NPI between ER-alpha and ER-beta predominant cohorts or between ER+ and ER- cohorts.


CONCLUSIONS
This study identifies the existence of a subgroup of ER+ patients in whom Tamoxifen therapy may be inappropriate and has significant implications for adjuvant therapy of primary breast cancer.
Balfe
P
P
Department of Surgery and BreastCheck Eccles Unit, Mater Misericordiae Hospital, Dublin, Ireland. pbalfep@hotmail.com
McCann
A
A
McGoldrick
A
A
McAllister
K
K
Kennedy
M
M
Dervan
P
P
Kerin
M J
MJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000235:genetics*; D001943:Breast Neoplasms / Q000453:epidemiology / Q000235:genetics*; D018270:Carcinoma, Ductal, Breast / Q000453:epidemiology / Q000235:genetics*; D018275:Carcinoma, Lobular / Q000453:epidemiology / Q000235:genetics*; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D011446:Prospective Studies; D011960:Receptors, Estrogen / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012307:Risk Factors; D016387:Women's Health
D014408:Biomarkers, Tumor; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D011960:Receptors, Estrogen