Condition category
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Background and study aims
The role of estrogen receptor beta (ER-β) in human breast cancer remains unclear. There is no consensus regarding the clinical utility of an ER-β assay. Some studies have suggested that ER-β may oppose the actions of estrogen receptor alpha (ER-α), and clinical evidence has indicated that the loss of ER-β expression is associated with a poor prognosis and resistance to endocrine therapy. The objective of the present study is to determine the role of ER-β and the ER-α/ER-β ratio in predicting the response to endocrine therapy and whether different regimens have any effect on ER-α and ER-β expression levels.

Who can participate?
Postmenopausal women with histologically confirmed invasive breast cancer without previous treatment for the disease (surgery, radio or chemotherapy).

What does the study involve?
Patients with operable breast cancers will be randomly allocated to one of three groups: receive 26 days of treatment with anastrozole (1 mg/day), tamoxifen (20 mg/day) or placebo. The pre- and post-hormone therapy samples will be placed in tissue microarray blocks and submitted to immunohistochemical assay. Biomarker statuses (ER-β, ER-α and Ki67) will be obtained by comparing each immunohistochemical evaluation of the pre- and post-surgery samples using the semi-quantitative Allred´s method.

What are the possible benefits and risks of participating?
There will be no immediate direct benefit to those taking part. A treatment period of 26 days was chosen for this study because this is the average time needed to complete routine preoperative testing in most Brazilian institutions, justifying the use of placebo without negative consequences to the patients. In addition, the period of drug exposure is too short to observe the most important side effects of treatment in the anastrozole and tamoxifen groups.

Where is the study run from?
Two centres are taking part in this study. Patients will be recruited at Pérola Byington Hospital, Sao Paulo / Brazil and Federal University of Sao Paulo Hospital, Sao Paulo / Brazil.

When is the study starting and how long is it expected to run for?
The study started in October 2010 and will run for 36 months or until the required number of 90 patients have been recruited and evaluated.

Who is funding the study?
Senology Discipline, Department of Gynecology, Federal University of Sao Paulo – UNIFESP (Brazil)

Who is the main contact?
Marcelo Madeira

Trial website

Contact information



Primary contact

Mr Marcelo Madeira


Contact details

R. Sampaio Viana
Sao Paulo

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Estrogen Receptor Beta (ER-β) as a predictor of endocrine therapy responsiveness – A randomised neoadjuvant trial comparison between Anastrozole and Tamoxifen for the treatment of postmenopausal breast cancer


Study hypothesis

Several studies have suggested that the expression of ER-β independently predicts a better disease-free survival in breast cancer patients. Our hypothesis is that the measurement of ER-β or the ratio of ER-α/ER-β expression in breast cancer patients may help predict tamoxifen and anastrozole responsiveness in the neoadjuvant therapy.

Ethics approval

Human Investigation Committees of Federal University of São Paulo (UNIFESP) and Pérola Byington Hospital, 30-Jul-2010, ref: CEP0894/10 (Brazil)

Study design

Randomised prospective controlled double-blind study

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please contact or to request a patient information sheet


Breast Cancer


Patients with operable breast cancers will receive orally treatment with anastrozole (1 mg/day), tamoxifen (20 mg/day) or placebo during 26 days.

Intervention type



Not Specified

Drug names

Anastrazole, tamoxifen

Primary outcome measure

To determine the role of ER-β in predicting the response to breast cancer therapy with anastrozole and tamoxifen we will observe the expression of Ki67 (cell proliferation marker) in tumor biopsy samples taken before and after treatment (26 days) of ER-β-positive and ER-β-negative breast cancer patients.

Secondary outcome measures

The ER-α/ER-β expression ratio predicting the response to breast cancer endocrine therapy and whether different regimens of treatment have any effect on ER-α and ER-β expression levels.

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

Histologically confirmed invasive breast cancer in women who were postmenopausal, which is defined as no menstruation periods over the last 12 months and/or an FSH level within the postmenopausal range.

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. The presence of endocrine disease, metastatic disease, inflammatory breast cancer (T4d)
2. History of thromboembolism
3. Use of hormone replacement therapy (HRT) or previous treatment for breast cancer (surgery, radio or chemotherapy). Patients who do not comply with the prescribed medication regimen or postpone surgery are also excluded from the study. Patients who had previously taken HRT may be included if they have stopped hormonal treatment at least six months prior to trial randomisation.

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

R. Sampaio Viana, 580
Sao Paulo

Sponsor information


Federal University of Sao Paulo (Brazil)

Sponsor details

Senology Discipline
Department of Gynecology
R. Botucatu
Sao Paulo

Sponsor type




Funder type


Funder name

Federal University of Sao Paulo (UNIFESP) - Senology Discipline, Department of Gynecology (Brazil)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Basic results (scientific)

Publication list

2013 results in:

Publication citations

  1. Results

    Madeira M, Mattar A, Logullo AF, Soares FA, Gebrim LH, Estrogen receptor alpha/beta ratio and estrogen receptor beta as predictors of endocrine therapy responsiveness-a randomized neoadjuvant trial comparison between anastrozole and tamoxifen for the treatment of postmenopausal breast cancer., BMC Cancer, 2013, 13, 425, doi: 10.1186/1471-2407-13-425.

Additional files

Editorial Notes