Personalized tamoxifen dosing: can a PET scan show the way?

NCT ID NCT04174352

First seen Jan 11, 2026 · Last updated Jun 19, 2026 · Updated 20 times

Summary

This pilot study tests whether a special PET scan (FES-PET/CT) can help doctors find the best dose of tamoxifen for people with metastatic breast cancer that has an ESR1 mutation. These mutations can make standard tamoxifen doses less effective. The study will enroll 12 participants and use the scan to measure how well tamoxifen blocks estrogen receptors at different dose levels. The goal is to identify the optimal dose for future studies.

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This is a summary of the original study . Summaries may miss details or leave out important information. Before applying or accepting participation, make sure you have read and understood the full study. Curemydisease.com takes no responsibility whatsoever for anything missed, misunderstood, or acted upon as a result of our summary — we know it does not capture everything.

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Contacts and locations

Study contacts

  • Contact

    Phone: •••-•••-•••• Email: •••••@•••••

Locations

  • University of Wisconsin Carbone Cancer Center

    RECRUITING

    Madison, Wisconsin, 53792, United States

    Contact Phone: •••-•••-•••• Email: •••••@•••••

    Contact

  • Wisconsin Oncology Network (WONIX) sites

    NOT_YET_RECRUITING

    Madison, Wisconsin, 53792, United States

    Contact Phone: •••-•••-•••• Email: •••••@•••••

What this could mean

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

Active substance

Tamoxifen

What this could lead to

If successful, this could show how to personalize tamoxifen dosing for patients with ESR1 mutations, potentially improving treatment effectiveness.

What could go wrong

This is a very small, early-phase pilot study with only 12 participants. It is designed to find the right dose, not to prove the treatment works, so results may not lead to immediate changes in care.

Conditions

The condition(s) this trial relates to.

breast carcinoma estrogen-receptor positive breast cancer

As listed by the trial registrant

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