A Phase 2 interventional study of F-18 16 Alpha-Fluoroestradiol and Positron Emission Tomography in Estrogen Receptor Positive, Primary or Recurrent Breast Carcinoma and Stage IV Breast Cancer AJCC v6 and v7, sponsored by University of Washington. Active, not recruiting at 1 site in United States. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-07-01.
Sponsored by University of Washington · Phase 2, Interventional, and Diagnostic
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.
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.
12,544 studies on the registry are indexed under Breast Neoplasms; 2,892 are open to participants now.
This study's enrollment of 2 is below the median of 72 across 9,302 interventional studies indexed under Breast Neoplasms.
Browse Breast Neoplasms studies →University of Washington is the lead sponsor of 1,397 studies on the registry; 225 are open to participants now.
Of its 154 completed or terminated interventional studies of FDA-regulated products, 132 (86%) have results posted.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
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.
Drug: F-18 16 Alpha-Fluoroestradiol · Procedure: Positron Emission Tomography · Procedure: Computed Tomography · Drug: Fludeoxyglucose F-18 · Other: Laboratory Biomarker Analysis
Undergo F-18 FES PET/CT
Also known as: F-18 FES, FES, Fluorine-18 16 alpha-fluoroestradiol, Fluoroestradiol F-18
Undergo F-18 FES PET/CT
Also known as: Medical Imaging, PET Scan, Positron Emission Tomography Scan, Positron-Emission Tomography
Undergo F-18 FES PET/CT
Also known as: CAT Scan, Computerized Axial Tomography, CT scan
Undergo FDG PET/CT
Also known as: FDG, Fluorodeoxyglucose F18, 18FDG
Undergo FDG PET/CT
Also known as: Medical Imaging, PET, PET Scan
Undergo FDG PET/CT
Also known as: CAT Scan
Correlative studies
Change in F-18 16 Alpha-fluoroestradiol (FES) Standardized Uptake Value (SUV) - Avg SULmax
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.
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)
F-18 16 Alpha-fluoroestradiol (FES) Uptake
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.
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)
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)
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.
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)
Time to Disease Progression
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.
Time frame: From start of therapy up to 20 years
| Milestone | Diagnostic (F-18 FES PET/CT) |
|---|---|
| Started | 2 |
| Completed | 2 |
| Not completed | 0 |
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.
| Percentage decrease in avgSUL | Diagnostic (F-18 FES PET/CT) |
|---|---|
| Change in F-18 16 Alpha-fluoroestradiol (FES) Standardized Uptake Value (SUV) - Avg SULmax | 78 (77 to 79) |
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.
| average SUVmax | Diagnostic (F-18 FES PET/CT) |
|---|---|
| FES scan 1 | 5.7 (4.6 to 6.8) |
| FES scan 2 | 1.4 (1.0 to 1.7) |
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.
| participants with increased FES uptake | Diagnostic (F-18 FES PET/CT) |
|---|---|
| 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) | 0 |
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.
Results for this outcome have not been posted.
Collected over 24 hours after each FES PET/CT study (the time-frame of F18-FES decay). Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Diagnostic (F-18 FES PET/CT) | 0/2 (0%) | 0/2 (0%) | 0/2 (0%) |
| Age, Categorical(Participants) | Diagnostic (F-18 FES PET/CT) |
|---|---|
| <=18 years | 0 |
| Between 18 and 65 years | 0 |
| >=65 years | 2 |
| Age, Continuous(years) | Diagnostic (F-18 FES PET/CT) |
|---|---|
| Mean | 71 (70 to 71) |
| Sex: Female, Male(Participants) | Diagnostic (F-18 FES PET/CT) |
|---|---|
| Female | 2 |
| Male | 0 |
| Ethnicity (NIH/OMB)(Participants) | Diagnostic (F-18 FES PET/CT) |
|---|---|
| Hispanic or Latino | 0 |
| Not Hispanic or Latino | 2 |
| Unknown or Not Reported | 0 |
| Race (NIH/OMB)(Participants) | Diagnostic (F-18 FES PET/CT) |
|---|---|
| American Indian or Alaska Native | 0 |
| Asian | 0 |
| Native Hawaiian or Other Pacific Islander | 0 |
| Black or African American | 0 |
| White | 2 |
| More than one race | 0 |
| Unknown or Not Reported | 0 |
| Region of Enrollment(participants) | Diagnostic (F-18 FES PET/CT) |
|---|---|
| United States | 2 |
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