Breast Cancer FemalePhase 3POWER IINCT06507618
Pre-Operative Window of ET to Inform RT Decisions (POWER II)
A Phase 3 study testing Tamoxifen, Letrozole, Anastrozole, or Exemestane in people with Breast Cancer Female, run by University of Virginia at 6 sites in United States.
Trial summary
This is a Phase III, multisite exploratory study for women ≥ 65 years of age with early stage estrogen receptor positive (ER+) breast cancer. These individuals will be treated randomly assigned to one of two groups: Intervention, treated with 3 months of pre-operative endocrine therapy (pre-ET) OR Control… Read more about this study
- Who is it for?
- Ages 65 years and older, women only
- Conditions the study is for
- Breast Cancer Female
- What is being tested?
- Tamoxifen, Letrozole, Anastrozole, or Exemestane
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 354 participants
- Where
- 6 sitesUnited States
- Study dates
- 19 Jul 2024to 1 Mar 2034
- Phase
- Phase 3
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 65 years and older
- Women only
- No healthy volunteers
- Older adult
Who may be able to join
- Diagnosis of ER+, PR +/-, and HER2- non amplified invasive breast cancer and clinically negative nodes
- ECOG performance status 0-2
- Females, aged ≥ 65 years
- Patient is eligible for BCS and opted for BCS
- Patient is a candidate for radiation therapy
- Patient is a candidate for endocrine therapy (tamoxifen or an aromatase inhibitor)
Show all 10Show fewer
- Ability to take oral medication and be willing to adhere to endocrine therapy for the 3-month period prior to BCS
- Agreement to adhere to Lifestyle Considerations (details in protocol) throughout study duration
- Provision of signed and dated informed consent form
- Stated willingness to comply with all study procedures and availability for the duration of the study
Who cannot join
- Bilateral synchronous breast cancer
- Multicentric disease
- Prior use of Tamoxifen or aromatase inhibitors
- History of ipsilateral breast radiation therapy
- Has a known additional malignancy that is progressing and/or requires active treatment with cytotoxic chemotherapy or radiation therapy. Malignancies deemed stable and low risk for complication per investigator's judgment may be allowed after discussion with multi-site PI.
- Current or planned use of a strong CYP2D6 inhibitor (e.g., Fluvoxamine, Paroxetine) and is not able to receive an endocrine therapy agent that does not use the CYP2D6 pathway.
Trial locations and contacts
6 sites in 1 country. Contact the study team or a site near you to ask about taking part.
6 sites in 1 country
United States6 sites, 6 recruiting
- Recruiting
University of Virginia
Charlottesville, Virginia, 22903
Meagan Miller, (434) 243-8101, aey8fc@uvahealth.org
- Recruiting
University of Virginia Community Health
Culpeper, Virginia, 22701
Ali Mahjoub, AM3CG@uvahealth.org
- Recruiting
INOVA Schar Cancer
Fairfax, Virginia, 22031
Shawna Willey, 5714724724
- Recruiting
Yale University
New Haven, Connecticut, 06511
Cameron Groshek, 8604161250, cameron.groshek@yale.edu
- Recruiting
Riverside Health System
Newport News, Virginia, 23601
- Recruiting
Virginia Commonwealth University
Richmond, Virginia, 23298
Deja Wortham, worthamdn@vcu.edu
About this study
Official title: A Randomized, Phase III Trial of Pre-Operative Window of Endocrine Therapy to Inform Radiation Therapy Decisions in Older Women With Early-Stage Breast Cancer (POWER II)
This is a Phase III, multisite exploratory study for women ≥ 65 years of age with early stage estrogen receptor positive (ER+) breast cancer. These individuals will be treated randomly assigned to one of two groups:
Intervention, treated with 3 months of pre-operative endocrine therapy (pre-ET) OR Control, participants follow standard of care and proceed directly to breast cancer surgery.
Both arms will be assessed for tolerance and compliance to the endocrine therapy by patient reported outcome (PRO) measures (patient surveys).
Read the detailed description
Early-stage, estrogen receptor positive (ER+) breast cancer is traditionally treated with breast conserving surgery (BCS), radiation therapy (RT) and 5-10 years of adjuvant endocrine therapy (AET). Radiation therapy (RT) omission is an established treatment paradigm for women 65 years and older with ER+, node negative, small (≤ 3 cm) breast cancer. Despite the option for RT omission being recommended in the National Comprehensive Cancer Network (NCCN) guidelines, multiple modern studies demonstrate that a majority of older women still receive RT, raising concern for over-treatment. Conversely, there are a portion of patients who choose to omit RT but are not able to tolerate AET and thus are at risk for under-treatment and worse oncologic outcomes.
In the POWER I trial, patients were treated with 90 days of pre-operative endocrine therapy (pre-ET) as a window to establish endocrine therapy (ET) tolerance. The POWER I trial prospectively validated 90 days of pre-operative ET to determine if it could be used as a tool to inform adjuvant RT decisions and recommendations by patients and physicians respectively. Ninety days of pre-ET was shown to influence patient and physician preferences regarding adjuvant RT.
In the POWER II trial, participants will be randomized to treatment on either a) an intervention arm consisting of a 90-day window of pre-ET or b) the standard of care (control) arm in which participants proceed directly to BCS. In both arms, the decision to omit or administer adjuvant RT will be made by the treating physicians and patients. While not required per protocol, all patients will be recommended for AET if deemed appropriate by their oncologist, and adherence through 2 years will be monitored. The POWER I study revealed that pre-ET impacts patients' and physicians' decisions regarding adjuvant therapy and facilitates adjuvant therapy decisions that meld patient preferences and side effect tolerance. The purpose of the POWER II study is to examine whether 90 days of pre-ET results in a decrease in the number of (1) patients being treated with BCS alone and (2) patients treated with BCS+RT+AET. Adherence to AET will be defined as taking AET at 2 years post-BCS.
- Conditions
- Breast Cancer Female
- Being tested
- Tamoxifen, Letrozole, Anastrozole, or Exemestane
- Keywords
- breast cancer, endocrine therapy, radiation, letrozole, anastrozole, exemestane, tamoxifen, survey, questionnaire, geriatric
- Medical subject headings
- Breast Neoplasms
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Tamoxifen, Letrozole, Anastrozole, or ExemestaneDrug
Also called Endocrine Therapy
Choice and dose of neoadjuvant endocrine therapy at the discretion of the treating medical oncologist.
| Study group | Role | What they receive |
|---|---|---|
| Intervention Arm | Experimental | 90 days of pre-ET (endocrine therapy - tamoxifen or aromatase inhibitor) before Breast Cancer Surgery Receives: Drug: Tamoxifen, Letrozole, Anastrozole, or Exemestane |
| Control Arm | No intervention | Will proceed directly to Breast Cancer Surgery |
What is being measured
The primary outcome is the main question the study is designed to answer.
Proportion of participants who omit Radiation Therapy (RT) and are non-adherent to Endocrine Therapy (ET)
Proportion of participants who omit RT and are non-adherent to ET as measure through the 24-month adjuvant follow-up visit
Measured: 24 months
Proportion of participants who are treated with Breast Cancer Surgery (BCS) + RT + AET
Proportion of participants who are treated with BCS + RT + AET as measured through the 24-month adjuvant follow-up visit
Measured: 24 months
Secondary outcomes (15)
Treatment with pre-ET and its impact on Decision Conflict
Using Patient Reported Outcomes (PRO) assessments of Decisional Conflict Scale (DCS) to determine whether treatment with pre-ET lessens Decision Conflict. The DCS is a validated measure of patient perceptions of uncertainty surrounding treatment choices. The minimum score is a 0, which is interpreted as no decisional conflict, and the maximum score is 64, which is interpreted as the highest decisional conflict.
Measured: 24 months
Treatment with pre-ET and its impact on Decision Regret
Using Patient Reported Outcomes (PRO) assessments of Decision Regret Scale (DRS) to determine whether treatment with pre-ET lessens Decision Regret. The DRS is a validated, 5-item scale that measures self-reported regret after health care decisions. DRS scores range from 0 (no regret) to 100 (high regret).
Measured: 24 months
Assessing whether patient's final treatment correlates with their beliefs about breast cancer
Using the PRO assessment "Beliefs about Illness Questionnaire (BIP-Q)" to determine patient's beliefs about breast cancer. The BIP-Q is a validated survey to assess cognitive and emotional perceptions of illness.
Measured: 7 months
Assessing whether patient's final treatment correlates with their beliefs about breast cancer
Using the PRO assessment "Beliefs about Medicine Questionnaire (BMQ)" to determine patient's beliefs about breast cancer. The BMQ is a validated survey designed to capture patients' perceptions about medicines and medicine adherence.
Measured: 7 months
Assessing whether patient's final treatment correlates with their beliefs about breast cancer
Using the PRO assessment "Perceived Sensitivity to Medicine (PSM)" to determine patient's beliefs about breast cancer. The PSM is a validated 5-question survey designed to capture patients' opinions regarding their sensitivity to medications.
Measured: 7 months
Assessing whether treatment with pre-ET leads to improved Health Related Quality of Life compared to those treated with standard of care
Using PRO Assessments: EORTC Quality of Life questionnaires (QLQ-C30) to determine whether treatment with pre-ET leads to improved health-related quality of life compared to those treated with standard of care
Measured: 24 months
Assessing whether early side effects of ET correlate with patient treatment group within study arms
Using the PRO Assessment "Breast Cancer Prevention Trial Symptom Checklist (BCPT-SCL)" to assess whether early side effects of ET correlate with patient treatment group within study arms
Measured: 24 months
Assessing whether early side effects of ET correlate with patient treatment group within study arms
Using the PRO Assessment "Center for Epidemiologic Study Depression Scale Revised (CESD-R)" to assess whether early side effects of ET correlate with patient treatment group within study arms
Measured: 24 months
To obtain data on local recurrence
Local recurrence as measured through the 5 year adjuvant follow-up period
Measured: 5 years
To obtain data on regional recurrence
Regional recurrence as measured through the 5 year adjuvant follow-up period
Measured: 5 years
To obtain data on contralateral breast cancer
Contralateral breast cancer as measured through the 5 year adjuvant follow-up period
Measured: 5 years
To obtain data on distant metastases
Distant metastases as measured through the 5 year adjuvant follow-up period
Measured: 5 years
To obtain data on disease free survival
Disease free survival (DFS) as measured through the 5 year adjuvant follow-up period
Measured: 5 years
To obtain data on cancer specific survival
Cancer specific survival as measured through the 5 year adjuvant follow-up period
Measured: 5 years
To obtain data on overall survival
Overall survival (OS) as measured through the 5 year adjuvant follow-up period
Measured: 5 years
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted18 Jul 2024
- Study start19 Jul 2024
- Primary completion30 Jun 2029 (estimated)
- Study completion1 Mar 2034 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Breast Cancer FemaleStudies of the same condition, open and under way.
- More trials run by University of VirginiaThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 3
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 354 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Virginia
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Shayna Showalter, MD, University of Virginia
- Investigators
- Shayna L Showalter, MD, Principal investigator, University of Virginia
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06507618
- Sponsor's protocol ID
- HSR230513
- Acronym
- POWER II
- Status last verified
- Feb 2026
- First submitted
- 20 Jun 2024
- Last updated
- 30 Jun 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 30 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Randomized, Phase III Trial of Pre-Operative Window of Endocrine Therapy to Inform Radiation Therapy Decisions in Older Women With Early-Stage Breast Cancer (POWER II)
- ClinicalTrials.gov ID
- NCT06507618
- Acronym / sponsor ID
- POWER II / HSR230513
- Conditions
- Breast Cancer Female
- Keywords
- breast cancer, endocrine therapy, radiation, letrozole, anastrozole, exemestane, tamoxifen, survey
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 354 participants (estimated)
- Lead sponsor
- University of VirginiaUniversity, hospital or other
- Study start
- 19 Jul 2024 (actual)
- Primary completion
- 30 Jun 2029 (estimated)
- Study completion
- 1 Mar 2034 (estimated)
- First posted
- 18 Jul 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This is a Phase III, multisite exploratory study for women ≥ 65 years of age with early stage estrogen receptor positive (ER+) breast cancer. These individuals will be treated randomly assigned to one of two groups:
Intervention, treated with 3 months of pre-operative endocrine therapy (pre-ET) OR Control, participants follow standard of care and proceed directly to breast cancer surgery.
Both arms will be assessed for tolerance and compliance to the endocrine therapy by patient reported outcome (PRO) measures (patient surveys).
Detailed description
Early-stage, estrogen receptor positive (ER+) breast cancer is traditionally treated with breast conserving surgery (BCS), radiation therapy (RT) and 5-10 years of adjuvant endocrine therapy (AET). Radiation therapy (RT) omission is an established treatment paradigm for women 65 years and older with ER+, node negative, small (≤ 3 cm) breast cancer. Despite the option for RT omission being recommended in the National Comprehensive Cancer Network (NCCN) guidelines, multiple modern studies demonstrate that a majority of older women still receive RT, raising concern for over-treatment. Conversely, there are a portion of patients who choose to omit RT but are not able to tolerate AET and thus are at risk for under-treatment and worse oncologic outcomes.
In the POWER I trial, patients were treated with 90 days of pre-operative endocrine therapy (pre-ET) as a window to establish endocrine therapy (ET) tolerance. The POWER I trial prospectively validated 90 days of pre-operative ET to determine if it could be used as a tool to inform adjuvant RT decisions and recommendations by patients and physicians respectively. Ninety days of pre-ET was shown to influence patient and physician preferences regarding adjuvant RT.
In the POWER II trial, participants will be randomized to treatment on either a) an intervention arm consisting of a 90-day window of pre-ET or b) the standard of care (control) arm in which participants proceed directly to BCS. In both arms, the decision to omit or administer adjuvant RT will be made by the treating physicians and patients. While not required per protocol, all patients will be recommended for AET if deemed appropriate by their oncologist, and adherence through 2 years will be monitored. The POWER I study revealed that pre-ET impacts patients' and physicians' decisions regarding adjuvant therapy and facilitates adjuvant therapy decisions that meld patient preferences and side effect tolerance. The purpose of the POWER II study is to examine whether 90 days of pre-ET results in a decrease in the number of (1) patients being treated with BCS alone and (2) patients treated with BCS+RT+AET. Adherence to AET will be defined as taking AET at 2 years post-BCS.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Intervention Arm | Experimental | Drug: Tamoxifen, Letrozole, Anastrozole, or Exemestane90 days of pre-ET (endocrine therapy - tamoxifen or aromatase inhibitor) before Breast Cancer Surgery |
| Control Arm | No intervention | –Will proceed directly to Breast Cancer Surgery |
Who may qualify
- Ages
- 65 years and older
- Sex
- Female only
- Healthy volunteers
- Not accepted
- Age groups
- Older adult
Key inclusion criteria (10 listed)
- Diagnosis of ER+, PR +/-, and HER2- non amplified invasive breast cancer and clinically negative nodes
- ECOG performance status 0-2
- Females, aged ≥ 65 years
- Patient is eligible for BCS and opted for BCS
- Patient is a candidate for radiation therapy
Key exclusion criteria (6 listed)
- Bilateral synchronous breast cancer
- Multicentric disease
- Prior use of Tamoxifen or aromatase inhibitors
- History of ipsilateral breast radiation therapy
- Has a known additional malignancy that is progressing and/or requires active treatment with cytotoxic chemotherapy or radiation therapy. Malignancies deemed stable and low risk for complication per investigator's judgment may be allowed after discussion with multi-site PI.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Tamoxifen, Letrozole, Anastrozole, or ExemestaneAlso: Endocrine TherapyChoice and dose of neoadjuvant endocrine therapy at the discretion of the treating medical oncologist. | Drug | Intervention Arm |
Primary outcome
Proportion of participants who omit Radiation Therapy (RT) and are non-adherent to Endocrine Therapy (ET)
Time frame: 24 months
Proportion of participants who omit RT and are non-adherent to ET as measure through the 24-month adjuvant follow-up visit
Proportion of participants who are treated with Breast Cancer Surgery (BCS) + RT + AET
Time frame: 24 months
Proportion of participants who are treated with BCS + RT + AET as measured through the 24-month adjuvant follow-up visit
15 secondary outcomes
Treatment with pre-ET and its impact on Decision Conflict
Time frame: 24 months
Treatment with pre-ET and its impact on Decision Regret
Time frame: 24 months
Assessing whether patient's final treatment correlates with their beliefs about breast cancer
Time frame: 7 months
Assessing whether patient's final treatment correlates with their beliefs about breast cancer
Time frame: 7 months
Assessing whether patient's final treatment correlates with their beliefs about breast cancer
Time frame: 7 months
Assessing whether treatment with pre-ET leads to improved Health Related Quality of Life compared to those treated with standard of care
Time frame: 24 months
Assessing whether early side effects of ET correlate with patient treatment group within study arms
Time frame: 24 months
Assessing whether early side effects of ET correlate with patient treatment group within study arms
Time frame: 24 months
To obtain data on local recurrence
Time frame: 5 years
To obtain data on regional recurrence
Time frame: 5 years
To obtain data on contralateral breast cancer
Time frame: 5 years
To obtain data on distant metastases
Time frame: 5 years
To obtain data on disease free survival
Time frame: 5 years
To obtain data on cancer specific survival
Time frame: 5 years
To obtain data on overall survival
Time frame: 5 years
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 30 Jun 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Shayna L Showalter, MD principal investigator
University of Virginia
6 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing Tamoxifen, Letrozole, Anastrozole, or Exemestane in people with Breast Cancer Female, run by University of Virginia at 6 sites in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 10 inclusion and 6 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 30 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 6 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Meagan Miller (434-243-8101, aey8fc@uvahealth.org), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Proportion of participants who omit Radiation Therapy (RT) and are non-adherent to Endocrine Therapy (ET) (time frame: 24 months). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 30 Jun 2026; AzTrials last refreshed its copy on 7 Nov 2026.