Evaluating Optimal Timing of Endocrine Therapy and Radiation Therapy in Early-stage Breast Cancer (REaCT-RETT)

Official Title

A Pragmatic Randomised, Multicentre Trial Evaluating Optimal Timing of Endocrine Therapy and Radiation Therapy in Early-stage Breast Cancer (REaCT-RETT)


REaCT-RETT will demonstrate the non-inferiority of concurrent compared to sequential endocrine therapy in patients receiving post-operative radiation therapy for early stage breast cancer.

Trial Description

Primary Outcome:

  • Endocrine toxicity
Secondary Outcome:
  • Radiotherapy toxicity
  • Rates of starting endocrine therapy and compliance
  • Direct Estimation of Health Utility Values
  • Incremental cost-effectiveness ratios
  • Exploratory analyses on evaluating radiation therapy toxicity
Clinical equipoise exists around the optimal time to start adjuvant endocrine therapy in patients who will receive post-operative radiation therapy for breast cancer. Patients receive either concurrent or sequential endocrine and radiation therapy, where concurrent therapy consists of endocrine therapy started before, with or during radiation therapy, while sequential treatment is defined as endocrine therapy starting after the completion of radiation therapy. A recent survey of Canadian oncologists showed that the main reason for prescribing sequential endocrine therapy was a concern that concurrent endocrine therapy and radiation therapy would worsen the toxicity of endocrine treatment. This is despite the absence of any clinical trial evidence to support this. Indeed, a recent systematic review by our group was unable to confirm or refute whether increased toxicities, related to the timing of endocrine therapy and radiation therapy actually exist in clinical practice. The investigators are therefore proposing a pragmatic randomised trial to assess whether or not concurrent endocrine therapy and radiation therapy worsens endocrine treatment-related symptoms in an era of modern endocrine and radiation therapy.

View this trial on ClinicalTrials.gov

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Canadian Cancer Society

These resources are provided in partnership with the Canadian Cancer Society