Serial FES PET/CT to Measure Hormone Expression in Patients Undergoing Endocrine Targeted Therapy

January 4, 2026 updated by: Delphine Chen, University of Washington

Serial [F-18] Fluoroestradiol (FES) PET Imaging to Evaluate Endocrine-targeted Therapy

This clinical trial studies use of F-18 16 alpha-fluoroestradiol ([F-18] FES) positron emission tomography (PET)/computed tomography (CT) in measuring tumor hormone receptor expression in patients undergoing endocrine-targeted therapy for newly diagnosed breast cancer or breast cancer that has come back or spread to other places in the body. Comparing results of diagnostic procedures done before, during, and after hormone therapy may help measure a patient's response to treatment.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Active, not recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

OUTLINE:

Patients undergo F-18 FES PET/CT scan at baseline. Patients also undergo F-18 FES PET/CT and FDG PET/CT between 1-12 weeks after starting therapy, and then 1-12 weeks after the second FES PET/CT scan. Repeat FDG PET may be omitted in patients on selective estrogen receptor degrader.

After completion of study, patients are followed up for up to 20 years.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
2

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • United States
    • Washington
      • Seattle, Washington, United States, 98109
        • Fred Hutch/University of Washington Cancer Consortium

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Adult, non-pregnant patients with biopsy-proven or clinically obvious primary, recurrent or metastatic breast cancer
  • Breast cancer from ER+ primary that is seen on other imaging tests. Tumor ER expression must have been confirmed by immunohistocytochemistry of primary tumor or recurrent disease.
  • At least one site of disease 1.5 cm or greater is needed to meet the spatial resolution limits of PET imaging.
  • Patients must have been off tamoxifen or other estrogen receptor blocking agents for at least 6 weeks and off chemotherapy for 3 weeks for the initial baseline FES.
  • Patients must be selected for an endocrine targeted therapy regimen for treatment of their breast cancer by the referring oncologist. Selected treatments may be part of experimental treatment protocols for which the patient would be separately consented.
  • Patients must be willing to undergo serial imaging procedures.
  • Patients must agree to allow access to clinical records regarding response to treatment and long term follow up.
  • Ability to understand and the willingness to sign a written informed consent document.

Exclusion Criteria:

  • An inability to lie still for the tests
  • Individuals weighing more than 300 lb. (this is the weight limit of the scanner table)
  • Pregnant or lactating. Women of childbearing potential with either a positive or no pregnancy test at baseline are excluded.
  • Any other life-threatening illness (e.g. serious, uncontrolled concurrent infection or clinically significant cardiac disease - congestive heart failure, symptomatic coronary artery disease, cardiac arrhythmia not well controlled with medication).
  • Use of tamoxifen, faslodex, DES or any other ER blocking agent < 6 weeks or chemotherapy < 3 weeks prior to imaging scan.
  • Uncontrolled diabetes mellitus (fasting glucose > 200 mg/dL)
  • Adult patients who require monitored anesthesia for PET scanning.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Diagnostic
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Diagnostic (F-18 FES PET/CT)
Patients undergo F-18 FES PET/CT scan at baseline. Patients also undergo F-18 FES PET/CT and FDG PET/CT between 1-12 weeks after starting therapy, and then 1-12 weeks after the second FES PET/CT scan. Repeat FDG PET may be omitted in patients on selective estrogen receptor degrader.
Other: Laboratory Biomarker Analysis
Correlative studies
Procedure: Computed Tomography
Undergo FDG PET/CT
Other Names:
  • CAT Scan
Procedure: Positron Emission Tomography
Undergo FDG PET/CT
Other Names:
  • PET
  • PET Scan
  • Medical Imaging
Procedure: Computed Tomography
Undergo F-18 FES PET/CT
Other Names:
  • CAT Scan
  • Computerized Axial Tomography
  • CT scan
Drug: F-18 16 Alpha-Fluoroestradiol
Undergo F-18 FES PET/CT
Other Names:
  • F-18 FES
  • FES
  • Fluorine-18 16 alpha-fluoroestradiol
  • Fluoroestradiol F-18
Drug: Fludeoxyglucose F-18
Undergo FDG PET/CT
Other Names:
  • 18FDG
  • FDG
  • Fluorodeoxyglucose F18
Procedure: Positron Emission Tomography
Undergo F-18 FES PET/CT
Other Names:
  • PET Scan
  • Positron Emission Tomography Scan
  • Positron-Emission Tomography
  • Medical Imaging

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Change in F-18 16 Alpha-fluoroestradiol (FES) Standardized Uptake Value (SUV) - Avg SULmax
Time Frame: From time of first F-18 FES-PET/CT scan to time of second F-18 FES-PET/CT scan (approximately 1-12 weeks)
FES uptake will be quantified using lean body mass adjusted SUV (SUL). Percentage change in FES average SULmax between baseline and a second FES scan will be calculated for up to 3 lesions per patient.
From time of first F-18 FES-PET/CT scan to time of second F-18 FES-PET/CT scan (approximately 1-12 weeks)
F-18 16 Alpha-fluoroestradiol (FES) Uptake
Time Frame: From time of first F-18 FES-PET/CT scan to time of second F-18 FES-PET/CT scan (approximately 1-12 weeks)
Quantitative measures of FES uptake for each disease site will be determined by drawing regions-of-interest on lesions to determine maximal FES uptake (SUVmax) per lesion. Up to 10 sites seen on the static torso survey will be quantified.
From time of first F-18 FES-PET/CT scan to time of second F-18 FES-PET/CT scan (approximately 1-12 weeks)
Proportion of Patients With a Threshold of Percentage Change, or That Surpass a Targeted Follow-up F-18 16 Alpha-fluoroestradiol (FES) Standardized Uptake Value (SUV)
Time Frame: From time of first F-18 FES-PET/CT scan to time of second F-18 FES-PET/CT scan (approximately 1-12 weeks)
The number of patients showing a 20% increase in FES uptake (SULmean or SUVmax) compared to baseline from the first to second scan using a 90% Wilson score binomial confidence interval.
From time of first F-18 FES-PET/CT scan to time of second F-18 FES-PET/CT scan (approximately 1-12 weeks)

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Time to Disease Progression
Time Frame: From start of therapy up to 20 years
Time to disease progression will be measured as the time from the start of endocrine therapy to the time the patient is first recorded as having disease progression.
From start of therapy up to 20 years

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of Washington

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Hannah Linden, Fred Hutch/University of Washington Cancer Consortium

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
July 10, 2021

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
October 1, 2021

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
April 30, 2041

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
December 30, 2020

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
December 30, 2020

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
December 31, 2020

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
January 22, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 4, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
October 1, 2025

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • RG1007834
  • 10465 (Other Identifier: Fred Hutch/University of Washington Cancer Consortium)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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