A Trial of 15 Fraction vs 25 Fraction Pencil Beam Scanning Proton Radiotherapy After Mastectomy in Patients Requiring Regional Nodal Irradiation

November 20, 2025 updated by: Mayo Clinic

A Randomized Trial of 15 Fraction vs 25 Fraction Pencil Beam Scanning Proton Radiotherapy After Mastectomy in Patients Requiring Regional Nodal Irradiation

This is a randomized controlled trial to determine the safety of 15 fraction vs 25 fraction pencil beam scanning proton radiotherapy after mastectomy in patients requiring regional nodal irradiation. Proton therapy is recognized as a standard option for the delivery of radiotherapy for breast cancer.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

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.

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 (Actual)

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.
88

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 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Arizona
      • Scottsdale, Arizona, United States, 85259
        • Mayo Clinic in Arizona
    • Minnesota
      • Rochester, Minnesota, United States, 55905
        • Mayo Clinic in Rochester

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

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria

  • Age ≥ 18 years
  • Histologic confirmation of breast cancer resected by mastectomy with or without immediate reconstruction and chest wall and regional nodal irradiation planned.
  • pStage T1-T4N0-N3M0 or ypStage T0-4N0-N3M0 Note: The axilla must be staged by sentinel node biopsy alone, sentinel node biopsy followed by axillary node dissection, or axillary lymph node dissection alone
  • ECOG Performance Status (PS) 0 to 2. (Appendix I).
  • Negative pregnancy test done ≤7 days prior to registration, for women of childbearing potential only.
  • Radiotherapy must begin within 12 weeks of last surgery (breast or axilla) or last chemotherapy.

Note: Breast implants and expanders allowed

  • Able to and provides IRB approved study specific written informed consent
  • Ability to complete questionnaire (s) by themselves or with assistance
  • Able to complete all mandatory tests listed in section 4.0
  • Willing to return to enrolling institution for follow-up (during the active monitoring phase of the study)
  • Willing to provide tissue and blood samples for correlative research purposes.
  • Rochester and Arizona patients: Willing to sign consent onto the Mayo Clinic Radiotherapy Patient Outcomes Registry and Biobanking study, IRB number 15-000136
  • Rochester patients: Willing to sign consent onto Evaluation of cardiac function in patients undergoing proton beam or photon radiotherapy, IRB number 15-007443

Exclusion Criteria:

  • Medical contraindication to receipt of radiotherapy.
  • Severe active co-morbid systemic illnesses or other severe concurrent disease which, in the judgment of the investigator, would make the patient inappropriate for entry into this study or interfere significantly with the proper assessment of safety and toxicity of the prescribed regimens.
  • Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements or providing informed consent.
  • Active systemic lupus or scleroderma.
  • Pregnancy or women of childbearing potential who are sexually active and not willing/able to use medically acceptable forms of contraception
  • Prior receipt of ipsilateral breast or chest wall radiation that would result in significant overlap of radiation therapy fields. Prior contralateral radiotherapy for breast cancer is allowed.
  • Positive margins after definitive surgery
  • History of non-breast malignancies (except for in situ cancers treated only by local excision and basal cell and squamous cell carcinomas of the skin) within 5 years prior study entry
  • Inflammatory breast cancer
  • Recurrent Breast Cancer
  • Boosts to the chest wall after mastectomy. Nodal boosts are allowed.

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.
No Intervention: Conventional Fractionation
50.0 Gy (RBE) in 25 daily fractions
Experimental: Hypofractionation
40 Gy (RBE) in 15 daily fractions
Radiation: Hypofractionation
40 Gy (RBE) in 15 daily fractions

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
Complication Rate
Time Frame: 24 months
Will be defined as the percentage of women randomized who develop one or more of the following events: grade 3 or higher late adverse events; unplanned surgical intervention (not including planned serial fat grafting) in patients who undergo mastectomy with reconstruction.
24 months

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
Cosmesis
Time Frame: baseline, 2 years, and 5 years
measured by reviewing digital photographs and the 4 point (excellent, good, fair, poor) adaptation of the Harvard Cosmesis Scale
baseline, 2 years, and 5 years
Incidence of Acute Adverse Events
Time Frame: 5 years
Acute adverse events are defined using Common Terminology Criteria for Adverse Events (CTCAE) version 4. Grade 1 or 2 events occurring in at least 10% of patients are reported along with all grade 3 or higher events.
5 years
Incidence of Late Adverse Events
Time Frame: 5 years
Late adverse events are defined using CTCAE version 4. Grade 1 or 2 events occurring in at least 10% of patients are reported along with all grade 3 or higher events.
5 years
Reconstruction Failure
Time Frame: 5 years
A failure is defined as loss of the tissue expander or implant with the inability to replace it resulting in no final reconstruction or conversion to autologous reconstruction or revised with the addition of autologous reconstruction.
5 years
Quality of Life - Breast Cancer Outcomes
Time Frame: 5 years
measured by cosmesis evaluation and the Breast Cancer Treatment Outcome Scale (BCTOS)
5 years
Ipsilateral Breast Tumor Recurrence (IBTR) Incidence
Time Frame: 5 years
Will be defined as local recurrence from trial registration as a first event at 5 years. The IBTR cumulative incidence will be estimated using a competing risks method by treatment arm. The competing risks will be regional/distant breast cancer recurrence and death. The percentage of patients with IBTR is defined as the number of patients that have a IBTR divided by the number of patients treated in each arm.
5 years
Distant Recurrence Incidence
Time Frame: 5 years
Will assess metastatic cancer that has either been biopsy confirmed or clinically diagnosed as recurrent invasive breast cancer at 5 years. The percentage of patients with a distant recurrence is defined as the number of patients that have a distant recurrence divided by the number of patients treated in each arm.
5 years
Regional Recurrence Incidence
Time Frame: 5 years
Defined as invasive breast cancer in the axilla, regional lymph nodes, chest wall, and skin of the ipsilateral breast at 5 years. The percentage of patients with a regional recurrence is defined as the number of patients that have a regional recurrence divided by the number of patients treated in each arm.
5 years
Disease-free Survival (DFS) at 3 Years
Time Frame: 3 years post radiotherapy, up to 38 months
DFS is defined as the time from study registration until the occurrence, if any, of one of the following events: invasive IBTR, regional invasive breast cancer recurrence, distant breast cancer recurrence, death due to any cause, contralateral invasive breast cancer, and second primary non-breast invasive disease. DFS at 3 years will be reported as the percent of patients without a DFS event at 3 years post radiotherapy.
3 years post radiotherapy, up to 38 months
Overall Survival (OS) at 3 Years
Time Frame: 3 years post radiotherapy, up to 38 months
Overall survival is defined as the time from registration to death due to any cause. OS at 3 years is reported as the percentage of patients still alive and in follow up at 3 years post radiotherapy.
3 years post radiotherapy, up to 38 months

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.
Mayo Clinic

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: Robert W. Mutter, M.D., Mayo Clinic

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.
May 18, 2016

Primary Completion (Actual)

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.
October 21, 2020

Study Completion (Actual)

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.
November 18, 2023

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 19, 2016

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.
May 25, 2016

First Posted (Estimated)

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.
May 26, 2016

Study Record Updates

Last Update Posted (Estimated)

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.
December 4, 2025

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.
November 20, 2025

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.
August 1, 2024

More Information

Terms related to this study

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.
  • 15-006137
  • MC1631 (Other Identifier: Mayo Clinic)
  • NCI-2017-02362 (Registry Identifier: CTRP (Clinical Trial Reporting Program))

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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