Could estrogen shrink some triple negative breast tumors?

NCT ID NCT03941730

Ongoing Disease control Sponsor: Mayo Clinic Source: ClinicalTrials.gov ↗

First seen Jun 27, 2026 · Last updated Jun 27, 2026

Summary

This phase II trial at Mayo Clinic tests whether estradiol, a form of estrogen, can help patients with a specific subtype of triple negative breast cancer that has a receptor called ER beta. The study enrolls 8 women with advanced or metastatic disease. Researchers will measure how many patients have their disease controlled for at least 6 months.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance: estradiol (a form of estrogen)
What this could lead to: If it works, this could point toward a hormone-based treatment option for a subset of triple negative breast cancer patients whose tumors have a specific receptor (ER beta).
What could go wrong: This is a very small early-phase trial (only 8 participants) and results may not apply to all patients. Estrogen therapy can also stimulate some cancers, so safety is closely monitored.

This is an AI summary of the original study and may miss details. Read our disclaimer.

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Conditions

The condition(s) this trial relates to.

breast cancer breast carcinoma breast neoplasm triple-negative breast carcinoma

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

ADVANCED TRIPLE-NEGATIVE BREAST CARCINOMA ANATOMIC STAGE III BREAST CANCER AJCC V8 ANATOMIC STAGE IV BREAST CANCER AJCC V8 METASTATIC TRIPLE-NEGATIVE BREAST CARCINOMA RECURRENT BREAST CARCINOMA

Contacts and locations

Locations

FHCC South Lake Union

Seattle, Washington, 98109, United States
Mayo Clinic in Florida

Jacksonville, Florida, 32224-9980, United States
Mayo Clinic in Rochester

Rochester, Minnesota, 55905, United States
MedStar Georgetown University Hospital

Washington D.C., District of Columbia, 20007, United States
Montefiore Medical Center-Einstein Campus

The Bronx, New York, 10461, United States
UCSF Medical Center-Mission Bay

San Francisco, California, 94158, United States
University of Alabama at Birmingham Cancer Center

Birmingham, Alabama, 35233, United States
University of Chicago Comprehensive Cancer Center

Chicago, Illinois, 60637, United States
University of Washington Medical Center - Montlake

Seattle, Washington, 98195, United States

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