A Randomized Trial of Five Fraction Partial Breast Irradiation (RAPID2)

May 20, 2026 updated by: Ontario Clinical Oncology Group (OCOG)

A Randomized Trial of Five-Fraction Partial Breast Irradiation (RAPID2)

The primary objective of this study is to determine in women with node negative BC ≤3cm in size, if PBI compared to WBI, both given once-a-day over 1 week following BCS, is non-inferior for LR and reduces adverse cosmesis. The primary outcomes are LR and patient-assessed cosmesis at 3 years post randomization.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

This is a randomized, two-arm, single blinded trial comparing two radiation treatment modalities, PBI and WBI. Following BCS or on the completion of additional adjuvant chemotherapy, eligible and consenting patients with newly diagnosed and histologically confirmed invasive carcinoma of the breast (without evidence of metastatic disease); with microscopically clear resection margins of 1mm (or no residual disease on re-excision) and negative axillary node involvement will be randomized in a 1:1 fashion to receive either PBI (experimental group) or WBI (control group). Study participants will receive 26Gy in 5 fractions in both treatment arms, treated once per day, for a period of 5-7 days. Study participants will not be made aware of treatment allocation to prevent any potential bias in their assessment of cosmesis. Stratification factors include tumour size, estrogen receptor (ER) status, and clinical centre.

Study Type

Interventional

Enrollment (Estimated)

910

Phase

  • Phase 3

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 Backup

Study Locations

  • Australia
  • Canada
    • Alberta
      • Calgary, Alberta, Canada
        • Recruiting
        • Arthur J. E. Child Comprehensive Cancer Centre-Clinical Research Unit
        • Contact:
        • Contact:
        • Principal Investigator:
          • Jeffrey Cao
    • British Columbia
      • Victoria, British Columbia, Canada
        • Not yet recruiting
        • BCCA-Vancouver Island Cancer Centre
        • Principal Investigator:
          • Tanya Berrang
        • Contact:
    • Nova Scotia
      • Halifax, Nova Scotia, Canada
        • Recruiting
        • QEII HSC - Nova Scotia Cancer Centre
        • Principal Investigator:
          • Maureen Nolan
        • Contact:
    • Ontario
      • Barrie, Ontario, Canada
        • Recruiting
        • Royal Victoria Regional Health Centre
        • Contact:
        • Contact:
        • Principal Investigator:
          • Jessica Conway
      • Hamilton, Ontario, Canada
        • Recruiting
        • Juravinski Cancer Centre
        • Principal Investigator:
          • Do-Hoon Kim
        • Contact:
        • Contact:
      • London, Ontario, Canada
        • Recruiting
        • London Regional Cancer Centre
        • Principal Investigator:
          • Francisco Perera, MD
        • Contact:
      • Newmarket, Ontario, Canada
      • Sault Ste. Marie, Ontario, Canada
        • Recruiting
        • Algoma District Cancer Program
        • Contact:
        • Principal Investigator:
          • Stephane Thibodeau
      • Toronto, Ontario, Canada
        • Recruiting
        • Princess Margaret Hospital
        • Principal Investigator:
          • Jennifer Croke
        • Contact:
      • Toronto, Ontario, Canada
        • Recruiting
        • Toronto-Sunnybrook Health Sciences Centre - Odette Cancer Centre
        • Contact:
      • Windsor, Ontario, Canada, N8W2X3
        • Recruiting
        • Windsor Regional Cancer Centre
        • Contact:
        • Principal Investigator:
          • Khalid Hirmiz, MD
    • Quebec
    • Saskatchewan
      • Saskatoon, Saskatchewan, Canada, S7N 4H4

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

Ages Eligible for Study

50 years to 120 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

For inclusion in this study, patients must fulfill all of the following criteria:

  1. Female with a new histological diagnosis of invasive carcinoma of the breast with no evidence of metastatic disease (see AJCC TNM Cancer Staging, Appendix II).
  2. Treated by BCS with microscopically clear resection margins >= 1mm for invasive and non-invasive disease or no residual disease on re-excision.
  3. Negative axillary node involvement as determined by either sentinel lymph node biopsy or axillary node dissection or clinical assessment with a negative axillary ultrasound and/or biopsy, for women with unifocal tumours <= 2cm, histologic grade 1 or 2, ER or PR+ and HER2-ve that are being planned for endocrine therapy

Exclusion Criteria:

Patients who satisfy any of the following exclusion criteria are NOT eligible for this study:

  1. Age less than 50 years.
  2. Known to be BRCA 1 and/or BRCA 2 positive.
  3. Tumour size >3cm in greatest diameter on pathological examination.
  4. Evidence of extensive intraductal component (EIC) (defined as an invasive tumour with a ductal carcinoma in situ (DCIS) component comprising at least 25% and extending beyond the invasive component to surrounding normal breast tissue) with the following exception: smaller tumours with EIC where the combined size (of the invasive and DCIS components) are <= 3cm remain eligible
  5. Evidence of a DCIS component > 3cm
  6. Lobular carcinoma only.
  7. More than one primary tumour in different quadrants of the same breast (patients with multifocal breast cancer are eligible).
  8. Synchronous or previous contralateral breast cancer (patients with contralateral DCIS or LCIS are eligible).
  9. History of non-breast malignancy within the last 5 years other than treated non-melanoma skin cancer or treated in-situ carcinoma.
  10. Known pregnancy or currently lactating.
  11. Inability to localize tumour bed on CT planning (no evidence of surgical clips or seroma).
  12. Inability to plan the patient for the experimental technique.

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: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: Whole Breast Irradiation (WBI)
26 Gy in 5 fractions to the whole breast
Radiation: Whole Breast Irradiation (WBI)
The dose fractionation and prescription is 26Gy in 5 fractions to the PTV once per day over 5-7 days (due to holiday weekends up to 8 days will be acceptable).
Experimental: Partial Breast Irradiation (PBI)
26 Gy in 5 fractions to the tumour bed with a margin of normal tissue
Radiation: Partial Breast Irradiation (PBI)
The dose fractionation and prescription is 26Gy in 5 fractions to the PTV prescribed at the isocentre of the treatment fields treated once per day over 5-7 days (due to holiday weekends up to 8 days will be acceptable).

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Local Recurrence
Time Frame: Annually for 5 years post-randomization
Time from randomization to any evidence of tumour recurrence (invasive and non-invasive) in the treated breast.
Annually for 5 years post-randomization
Patient Assessment Cosmesis at 3 years
Time Frame: 3 and 5 years post-randomization
Cosmesis will be assessed by the patient using the Breast Cosmesis Questionnaire which incorporates the Modified EORTC Breast Cosmetic Rating System and the UK Patient Reported Outcomes Questions following BCS.
3 and 5 years post-randomization

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Distant Disease Free Survival (DDSF)
Time Frame: Annually for 5 years post-randomization.
Time from randomization to evidence of metastasis involving distant sites (e.g. bone, liver, lung, or brain).
Annually for 5 years post-randomization.
Disease Free Survival (DFS)
Time Frame: Annually for 5 years post-randomization.
Time from randomization to local recurrence, regional or distant recurrence, contralateral breast cancer, other second cancer, or death.
Annually for 5 years post-randomization.
Overall Survival
Time Frame: 3 years post-randomizaton.
Time from randomization to death of any cause.
3 years post-randomizaton.
Radiation Toxicity
Time Frame: 2 weeks and 3 months post-radiation treatment, then annually for 5 years post-randomization.
Acute (2 weeks and up to 3 months after completing RT) and late toxicity (beyond the 3 months after completing RT) will be assessed by clinical centre personnel using the NCI CTCAE version 5.0.
2 weeks and 3 months post-radiation treatment, then annually for 5 years post-randomization.
Nurse/Clinical Research Associate assessed cosmesis at 3 and 5 years.
Time Frame: 3 and 5 years post-randomization.
A nurse/Clinical Research Associate (CRA) assessment of cosmesis using the EORTC Breast Cosmetic Rating System. Nurses and CRAs will be training in assessing cosmesis using training slides and guide previously developed for other trials.
3 and 5 years post-randomization.
Patient Assessed Cosmesis at 5 years.
Time Frame: 5 years post-randomization.
Cosmesis will be assessed by the patient using the Breast Cosmesis Questionnaire which incorporates the Modified EORTC Breast Cosmetic Rating System13,27,42 and the UK Patient Reported Outcomes Questions following BCS.
5 years post-randomization.
Patient Reported Quality of Life
Time Frame: 2 weeks post-radiation treatment, then at 3 and 5 years post-randomization.
Patients will complete the EORTC Breast Cancer Quality of life questionnaire
2 weeks post-radiation treatment, then at 3 and 5 years post-randomization.

Collaborators and Investigators

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

Sponsor

Ontario Clinical Oncology Group (OCOG)

Collaborators

GenesisCare AU

Investigators

  • Principal Investigator: Timothy Whelan, M.D., Juravinski Cancer Centre and McMaster University

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)

November 20, 2023

Primary Completion (Estimated)

November 1, 2029

Study Completion (Estimated)

November 1, 2031

Study Registration Dates

First Submitted

June 7, 2022

First Submitted That Met QC Criteria

June 9, 2022

First Posted (Actual)

June 14, 2022

Study Record Updates

Last Update Posted (Actual)

May 22, 2026

Last Update Submitted That Met QC Criteria

May 20, 2026

Last Verified

March 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • OCOG-2022-RAPID2

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

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.

Clinical Trials on Breast Neoplasm Female

Clinical Trials on Whole Breast Irradiation (WBI)

Search Similar Trials

Sponsors and Collaborators

Medical Conditions

Drug Interventions

CROs by country

CROs in Türkiye

Conditions

Rare Diseases

Drug Interventions

Dietary Supplements

Sponsor/Collaborators

Locations

Subscribe