Evaluating Harms and Benefits of Endocrine Therapy in Patients ≥70 Years of Age With Lower Risk Breast Cancer

May 25, 2026 updated by: Ottawa Hospital Research Institute

A Randomised, Multicentre Trial Evaluating Harms and Benefits of Endocrine Therapy in Patients ≥70 Years of Age With Lower Risk Breast Cancer (REaCT-70)

The current standard of care for stage 1 hormone receptor-positive (HR+) breast cancer consists of breast-conserving surgery followed by adjuvant radiotherapy (RT) and endocrine therapy (ET) for at least 5 years. The benefit of adjuvant ET for older patients is mitigated because of their increase risk of death from other causes and shorter time horizon to live. Clinical and pathological factors such as low-intermediate grade, tumor size ≤2 cm, and older age have been used in a few studies to identify patients with a lower risk of recurrence that might benefit from adjuvant therapy de-escalation, i.e. omission of RT or ET. Since there is no dedicated randomized clinical trial (RCT) conducted to evaluate the omission of ET, there is clinical equipoise as to whether we can omit adjuvant ET in older patients with lower-risk early-stage breast cancer. Therefore, we propose a randomised, multicentre trial evaluating harms and benefits of endocrine therapy in patients ≥70 years of age with lower risk breast cancer.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
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

The current standard of care for stage 1 hormone receptor-positive (HR+) breast cancer consists of breast-conserving surgery followed by adjuvant radiotherapy (RT) and endocrine therapy (ET) for at least 5 years. The benefit of adjuvant ET for older patients is mitigated because of their increase risk of death from other causes and shorter time horizon to live. This population is also more likely to have additional comorbidities which can lead to higher treatment-related adverse events impacting quality of life and precipitating functional decline. Clinical and pathological factors such as low-intermediate grade, tumor size ≤2 cm, and older age have been used in a few studies to identify patients with a lower risk of recurrence that might benefit from adjuvant therapy de-escalation, i.e. omission of RT or ET. The body of evidence from small prospective studies, mathematical modelling study and retrospective analyses would suggest that the omission of ET in older patients with favourable HR+ breast cancer who had optimal local therapy (i.e. breast conserving surgery followed by adjuvant radiotherapy) does not compromise locoregional and survival outcomes. Since there is no dedicated randomized clinical trial (RCT) conducted to evaluate the omission of ET, there is clinical equipoise as to whether we can omit adjuvant ET in older patients with lower-risk early-stage breast cancer. Therefore, we propose a randomised, multicentre trial evaluating harms and benefits of endocrine therapy in patients ≥70 years of age with lower risk breast cancer.

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 (Estimated)

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.
500

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 4

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 Contact Backup

Study Locations

  • Canada
    • Alberta
      • Edmonton, Alberta, Canada, T6G 1Z2
        • Not yet recruiting
        • Cross Cancer Institute
    • Ontario
      • Kitchener, Ontario, Canada, N2G 1G3
        • Active, not recruiting
        • Waterloo Regional Health Network
      • London, Ontario, Canada, N6C 2R5
        • Active, not recruiting
        • London Health Sciences Centre
      • Markham, Ontario, Canada, L3P 7P3
        • Active, not recruiting
        • Oak Valley Health
      • Ottawa, Ontario, Canada, K1H8L6
        • Recruiting
        • The Ottawa Hospital
        • Contact:
          • Marie-France Savard, MD
          • Phone Number: 70170 6137377700
          • Email: msavard@toh.ca
      • Thunder Bay, Ontario, Canada, P7B 6V4
        • Active, not recruiting
        • Thunder Bay Regional Health Sciences Centre
    • Saskatchewan
      • Regina, Saskatchewan, Canada, S4T 7T1
        • Active, not recruiting
        • Allan Blair Cancer Centre
      • Saskatoon, Saskatchewan, Canada, S7N 4H4
        • Active, not recruiting
        • Saskatoon Cancer Centre

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

70 years and older (Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • New invasive estrogen and/or progesterone receptor-positive (ER+ and/or PR+), HER2-negative (HER2-) invasive breast carcinoma diagnosis as per ASCO-CAP guidelines
  • The primary tumour characteristics are either: Grade 1 and ≤3 cm on microscope exam, OR Grade 2 and ≤2 cm on microscope exam, OR Grade 3 and ≤1 cm on microscope exam
  • Treated with standard loco-regional therapy: breast conserving surgery followed by adjuvant radiotherapy OR total mastectomy
  • Axillary node-negative (cN0 or pN0)
  • Able to provide oral consent and complete questionnaires in French or English as per study protocol

Exclusion Criteria:

  • Metastatic cancer

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: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel 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: Omission of endocrine therapy
Other: No endocrine therapy
No endocrine therapy given
Active Comparator: Administration of endocrine therapy for at least 5 years
Other: Endocrine therapy
Endocrine therapy given for at least 5 years

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
Hierarchical composite endpoint (OS, iDFS, MDFS, QoL)
Time Frame: 5 years
The primary outcome is a hierarchical composite endpoint following the WIN-ratio approach. This composite endpoint includes overall survival (OS), invasive disease free survival (iDFS), metastatic disease free survival (MDFS), quality of life (QoL), joint pain, and hot flashes.
5 years

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
Overall survival
Time Frame: 5 years
Overall survival (OS) is the time from the date of surgery to the date of death due to any cause.
5 years
Invasive disease free survival
Time Frame: 5 years
Invasive disease free suvival (iDFS) is the time from the surgery until the first occurrence of invasive ipsilateral, loco-regional, contralateral and distant breast tumor recurrence or death due to any cause
5 years
Metastatic disease free survival
Time Frame: 5 years
Metastatic disease free survival (MDFS) is the time from the surgery until the first occurrence of distant breast tumor recurrence of death due to any causes
5 years
Health-related quality of life: FACT-B plus ES
Time Frame: Baseline, 26-weeks, 1-year, 2-years, 3-years, 4-years, 5-years
Health-related quality of life is measured using the Functional Assessment of Cancer Therapy - Breast (FACT-B) plus the Functional Assessment of Cancer Therapy - Endocrine Symptoms (FACT-ES). The FACT-B has a total score of 0 to 148. FACT-ES has a total score of 0 to 184. Higher scores indicate better quality of life.
Baseline, 26-weeks, 1-year, 2-years, 3-years, 4-years, 5-years
Hot flashes
Time Frame: Baseline, 26-weeks, 1-year, 2-years, 3-years, 4-years, 5-years
Hot flashes measured using the validated FACT-B plus ES (questions ES1-3). Worsening of hot flashes will be defined as an increase by 1 of the hot flashes score compared to baseline. Improvement will be defined as a decrease of 1 of the hot flashes score compared to baseline.
Baseline, 26-weeks, 1-year, 2-years, 3-years, 4-years, 5-years
Joint pain
Time Frame: Baseline, 26-weeks, 1-year, 2-years, 3-years, 4-years, 5-years
Joint pain measured using the validated FACT-B plus ES (question BRM1). Worsening of join pain will be defined as an increase by 1 of the joint pain score compared to baseline. Improvement of join pain will be defined as a decrease of 1 of the the join pain score compared to baseline.
Baseline, 26-weeks, 1-year, 2-years, 3-years, 4-years, 5-years
Health-related quality of life: FACT-G
Time Frame: Baseline, 26-weeks, 1-year, 2-years, 3-years, 4-years, 5-years
Health-related quality of life will be measured with the Functional Assessment of Cancer Therapy - General (FACT-G) 27-item questionnaire. FACT-G scores range from 0 to 108. Higher scores indicate better quality of life.
Baseline, 26-weeks, 1-year, 2-years, 3-years, 4-years, 5-years
Health-related quality of life: EQ-5D-5L
Time Frame: Baseline, 26-weeks, 1-year, 2-years, 3-years, 4-years, 5-years
The EQ-5D-5L questionnaire includes 6 self-reported quality of life items.
Baseline, 26-weeks, 1-year, 2-years, 3-years, 4-years, 5-years
Breast Cancer Specific Survival
Time Frame: 5 years
Breast Cancer Specific Survival (BCSS) is the time from the date of surgery to the date of death from the breast cancer.
5 years
Adverse events of interest
Time Frame: 5 years
The number of participants with each adverse events of interest: bone fracture, cerebrovascular event, thromboembolic event, cardiovascular event, secondary cancer, hospitalization and death.
5 years
Change in geriatric domains
Time Frame: Baseline, 1 year, 5 years
Change in geriatric domains (e.g. functional status, comorbidities, medications, nutritional status, cognitive function, and psychosocial status) using CARG score patient tool.
Baseline, 1 year, 5 years
Adherence with prescribed endocrine therapy
Time Frame: 26-weeks, 1-year, 2-years, 3-years, 4-years, 5-years
Adherence with prescribed endocrine therapy will be measured by the validated Five-Item Medication Adherence Report Scale (MARS-5 score) in Arm B only.
26-weeks, 1-year, 2-years, 3-years, 4-years, 5-years
Quality-adjusted life years (QALY)
Time Frame: 5 years
QALYs are estimated by multiplying the time spent in each health state by the corresponding utility value and summing these values across all model cycles over the time horizon.
5 years
Beliefs about Medicine Questionnaire - adjuvant endocrine therapy (BMQ-AET)
Time Frame: Baseline, 26-weeks, 1-year, 2-years, 3-years, 4-years, 5-years
Participants in arm B will complete the Beliefs about Medicine Questionnaire - adjuvant endocrine therapy (BMQ-AET). This includes 10 self-reported items.
Baseline, 26-weeks, 1-year, 2-years, 3-years, 4-years, 5-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.
Ottawa Hospital Research Institute

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: Marie-France Savard, MD, Ottawa Hospital Research Institute

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Helpful Links

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.
August 19, 2021

Primary Completion (Estimated)

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.
May 1, 2036

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.
May 1, 2036

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).
May 27, 2021

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.
June 4, 2021

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.
June 10, 2021

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.
May 28, 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.
May 25, 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.
May 1, 2026

More Information

Terms related to this study

Keywords

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.
  • REaCT-70

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

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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