Can a hormone coil shield the womb from estrogen's risks?
NCT ID NCT07795606
First seen Aug 31, 2026 · Last updated Sep 01, 2026 · Updated 1 time
Summary
This study looks at women aged 40 and older who still have a uterus and have started estrogen therapy for menopause symptoms or bone loss. Estrogen alone can thicken the womb lining, raising the risk of precancerous changes and cancer, so a progestogen is usually added for protection. Researchers will analyze anonymous insurance claims from over 450,000 women to compare how often women use estrogen alone, estrogen with the Mirena coil, or estrogen with other progestogens, and track rates of endometrial hyperplasia, cancer, abnormal bleeding, and hysterectomy over up to 10 years. The goal is to see how these treatments are used in real life and which approach may be linked with better outcomes.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- Mirena levonorgestrel-releasing intrauterine system (LNG-IUS) compared with other progestogen treatments during estrogen therapy
- What this could lead to
- If this study shows that Mirena is linked with lower rates of endometrial hyperplasia and cancer compared with other progestogens, it could support its wider use for endometrial protection during estrogen therapy.
- What could go wrong
- This is an observational study using insurance claims, not a controlled trial, so it can show associations but not prove cause and effect. The results may be affected by differences between the groups that are not fully accounted for.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Participants
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About 456,000 people
The number the study aims to enrol. It can still change while the study runs.
- Expected to start
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Aug 2026
An estimate. Start dates often move.
- Expected to finish
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Dec 2026
An estimate. End dates often move.
- Lead sponsor
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A company
The lead sponsor is a pharmaceutical, biotech, or medical-device company.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
Who is studied
The study population for the SHIELD-ET study are patients 40+ years of age with a uterus receiving estrogen therapy. Special populations or subpopulations among menopausal women (e.g. chemotherapy- or drug-induced menopause), as well as women without a uterus will be excluded.
- Ages
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40 years and older
- Sex
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Female participants only
- Healthy volunteers
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Not accepted
This study is not open to healthy volunteers. The entry requirements below say who it is open to.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: * At least one claim of estrogen therapy (ET) during the patient identification period (Index date: the first claim for ET) * Age ≥ 40 years at the index date * Patients with minimum continuous enrollment 12 months prior and 12 months at minimum after index date Exclusion Criteria: * Women without a uterus (claims of hysterectomy) in the 12-month baseline period * Use of any hormonal contraception in the 12-month baseline period * Claims indicative of atypical endometrial hyperplasia or endometrial cancer or heavy menstrual bleeding (HMB)/abnormal uterine bleeding (AUB)/postmenopausal bleeding (PMB), or any treatment for late state or metastatic endometrial cancer, in the baseline period. * Claims in the baseline period for any of the treatments of interest * Claims of chemotherapy/endocrine therapy in the baseline period
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As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
How to take part
Only the study team decides who joins. These are the ways to reach them.
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The places running it
2 sites. The list below names each one and where it is.
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The official record
ClinicalTrials.gov lists the study team's own contact details, including names and phone numbers. We don't republish those.
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A doctor treating you
A doctor who knows your case can contact a study site on your behalf, and can tell you whether this study is worth pursuing at all.
Contacts and locations
Locations
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Mirative MarketScan Commercial Claims and Encounters Database
Ann Arbor, Michigan, 48108, United States
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Optum Clinformatics™ Data Mart (CDM)
Eden Prairie, Minnesota, 55344, United States