A Study to See Whether Estrogen Can Slow the Growth of Some ER Positive Breast Cancers

What this trial studies

Some breast cancers have estrogen receptors (ER+). The investigators know that some ER+ tumours can be cured by hormone therapy alone while other ER+ breast cancers cannot. Currently, there is no perfect way to tell these groups apart nor do the investigators know why some respond when others do not. Research findings suggest that the two types of ER+ breast cancers differ in their response to estrogen with estrogen being toxic to one type and not the other.

Conditions in scope

• Estrogen Receptor Positive Breast Cancer

Interventions

• Estradiol (Drug) — Eligible participants will take 2 mg Estradiol 3 times daily for 7-14 days pre-surgery.

Who can join

Women only · Ages 55 Years and up

Inclusion criteria

• Female gender
• Estrogen receptor positive (ER+) breast cancer
• HER2 negative breast cancer
• Post-menopausal by greater than 5 years
• No previous hormonal replacement therapy
• Low to intermediate histologic grade
• ECOG Performance status of 0 of 1
• Adequate hematological, renal and hepatic function is required

Exclusion criteria

• Pre-menopausal women
• Locally advanced or metastatic breast cancer
• Current, previous or planning for pre-operative treatment with chemotherapy, hormone therapy including corticosteroids, radiation therapy for malignancy or other condition
• Known hypersensitivity or intolerance to estradiol
• Ischemic changes on baseline electrocardiogram
• Symptomatic but untreated cholelithiasis
• History of deep vein thrombosis, pulmonary embolism, stroke, acute myocardial infarction, congestive cardiac failure, untreated hypertension or known inherited hypercoagulable disorder
• Undiagnosed abnormal vaginal bleeding or prior history of endometrial cancer

Eligibility wording paraphrased from the public record. View the full criteria on ClinicalTrials.gov before contacting a site.

Where it’s happening

Status & timeline

• Overall status: Active, not recruiting
• Study type: Interventional
• Phase: PHASE2
• Start date: 2015-08
• Primary completion: 2018-07-30
• Last update posted: 2025-06-26
• First posted: 2014-09-12

Sponsor & contact

Lead sponsor: AHS Cancer Control Alberta (Other)

For trial site contact information, use the official record at ClinicalTrials.gov. Contact details change frequently and the public record is the source of truth.

Outcome measures

Primary outcomes

• To assess changes in breast cancer proliferation after a 7-14 day trial of estradiol in newly diagnosed estrogen receptor positive post-menopausal breast cancer patients prior to surgery. (end of 7-14 day treatment with estradiol)

Related ClearedRx care

If you’re reading this trial because you have menopause symptoms now, you don’t have to wait for a trial to access evidence-based care. ClearedRx prescribes the same FDA-approved and compounded HRT products that have been studied in trials like this one for decades.