Could a common diabetes drug stop breast cancer before it starts?

NCT ID NCT01905046

Ongoing Prevention Sponsor: Alliance for Clinical Trials in Oncology Source: ClinicalTrials.gov ↗

First seen Jun 25, 2026 · Last updated Jun 27, 2026 · Updated 1 time

Summary

This phase 3 trial tests whether taking metformin for 12 months can reduce abnormal cells in the breast tissue of women at high risk for breast cancer. Participants have conditions like atypical hyperplasia or a strong family history. Researchers compare metformin to a placebo to see if it lowers the chance of developing breast cancer.

What this could mean

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

Active substance: metformin (a common diabetes drug)
What this could lead to: If it works, this could show that a safe, inexpensive drug like metformin helps prevent breast cancer in women at high risk.
What could go wrong: This is a small, early-phase trial with only 86 participants, so results may not apply to everyone. Metformin can cause side effects like stomach upset, and it may not reduce cancer risk.

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 carcinoma in situ ductal breast carcinoma in situ lobular breast carcinoma in situ breast cancer prevention target

As listed by the trial registrant

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

ATYPICAL DUCTAL BREAST HYPERPLASIA BRCA1 MUTATION CARRIER BRCA2 MUTATION CARRIER DUCTAL BREAST CARCINOMA IN SITU LOBULAR BREAST CARCINOMA IN SITU

Contacts and locations

Locations

City of Hope Comprehensive Cancer Center

Duarte, California, 91010, United States
City of Hope South Pasadena

South Pasadena, California, 91030, United States
Cotton O'Neil Cancer Center / Stormont Vail Health

Topeka, Kansas, 66606, United States
Doctor's Hospital of Laredo

Laredo, Texas, 78041, United States
Duke University Medical Center

Durham, North Carolina, 27710, United States
Greenville Health System Cancer Institute-Andrews

Greenville, South Carolina, 29601, United States
Los Angeles County-USC Medical Center

Los Angeles, California, 90033, United States
M D Anderson Cancer Center

Houston, Texas, 77030, United States
Mayo Clinic in Rochester

Rochester, Minnesota, 55905, United States
Mount Sinai Hospital

New York, New York, 10029, United States
NYP/Columbia University Medical Center/Herbert Irving Comprehensive Cancer Center

New York, New York, 10032, United States
Ohio State University Comprehensive Cancer Center

Columbus, Ohio, 43210, United States
Prisma Health Cancer Institute - Butternut

Greenville, South Carolina, 29605, United States
Prisma Health Cancer Institute - Easley

Easley, South Carolina, 29640, United States
Prisma Health Cancer Institute - Eastside

Greenville, South Carolina, 29615, United States
Prisma Health Cancer Institute - Faris

Greenville, South Carolina, 29605, United States
Prisma Health Cancer Institute - Greer

Greer, South Carolina, 29650, United States
Prisma Health Cancer Institute - Seneca

Seneca, South Carolina, 29672, United States
Prisma Health Cancer Institute - Spartanburg

Boiling Springs, South Carolina, 29316, United States
Prisma Health Greenville Memorial Hospital

Greenville, South Carolina, 29605, United States
Roswell Park Cancer Institute

Buffalo, New York, 14263, United States
The Christ Hospital

Cincinnati, Ohio, 45219, United States
The Community Hospital

Munster, Indiana, 46321, United States
USC / Norris Comprehensive Cancer Center

Los Angeles, California, 90033, United States
University of Kansas Cancer Center

Kansas City, Kansas, 66160, United States
University of Oklahoma Health Sciences Center

Oklahoma City, Oklahoma, 73104, United States
University of Wisconsin Carbone Cancer Center

Madison, Wisconsin, 53792, United States

More trials for these conditions

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