Proton-Based Stereotactic Ablative Body Radiotherapy for Prostate Cancer

February 23, 2026 updated by: Bradley (Brad) Stish, Mayo Clinic

Proton-Based Stereotactic Ablative Body Radiotherapy (SABR) for Select Patients With Clinically Localized Prostate Cancer.

Stereotactic ablative body radiotherapy (SABR), or stereotactic body radiotherapy (SBRT), is a specialized form of radiotherapy used to treat prostate cancer with five treatments over two weeks, compared with a conventional eight-week or longer treatment course. The purpose of this trial is to investigate the effect that proton-based SABR has on quality-of-life in patients with localized prostate cancer. The evaluation and treatment will otherwise follow standard of care, and is not considered investigational.

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.

Detailed Description

Patients with low-risk or intermediate-risk, clinically localized prostate cancer will be evaluated according to standard of care medical practices. The evaluation includes history and examination, prostate-specific antigen (PSA) blood testing, and review of the prior prostate biopsy pathology report; radiology scans (for example, computed tomography [CT], magnetic resonance imaging [MRI], radionuclide bone scan) may be done also; recently completed testing may not need to be repeated. Small markers will be placed in the prostate to guide the proton beam stereotactic ablative body radiotherapy (SABR) treatments, and a hydrogel spacer may also be placed between the prostate and the rectum to push the rectum away from the prostate; the hydrogel spacer will dissolve a few months later. Participants will receive five (5) proton SABR treatments over a two (2) week time period. The study will have participants complete a quality-of life questionnaire and be evaluated for side-effects before starting SABR, at the end of SABR, at three (3), six (6) and 12 months after SABR, and then yearly for five (5) years. Evaluation of the cancer status will follow standard of care practices for at least ten (10) years.

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.
Observational

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.
150

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
    • 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

N/A

Sampling Method

Non-Probability Sample

Study Population

Adult male patients with prostate cancer.

Description

Inclusion Criteria:

  • Male, age ≥ 18 years.
  • Histological confirmation of adenocarcinoma of prostatic origin.
  • AJCC 7th edition clinical T1b-fdiabetes mellitus T2b.
  • AJCC clinical staging rules do not include findings from biopsy or imaging.
  • Gleason score ≤7 (International Society of Urological Pathologists grades 1-3).
  • Serum prostate-specific antigen ≤20 ng/mL.
  • Prostate-specific antigen <10 ng/mL, if dutasteride within last 90 days or finasteride within last 30 days.
  • Zubrod performance score 0-1.
  • Prostate volume <75-cc, determined by ultrasound, computed tomography or magnetic resonance imaging (modality with lesser volume is acceptable).
  • If neoadjuvant-concurrent androgen suppression is used, the prostate volume after the start of androgen suppression may be used.
  • American Urological Association voiding symptom index ≤15.
  • Ability to complete questionnaire(s) by themselves or with assistance.
  • Participation in a patient-reported outcomes survey program, inclusive of the Expanded Prostate Index Composite and CTCAE instruments.
  • Ability to provide informed written consent.

Exclusion Criteria:

  • Radiological- or pathologically-confirmed seminal vesicle invasion, lymph node involvement, or distant metastatic disease.

    • Radiological- or biopsy-confirmed extraprostatic tumor extension without AJCC 7th edition clinical T3a classification remain eligible.
  • Prior or anticipated external radiotherapy or brachytherapy, transurethral resection of the prostate, prostatic cryoablation/focused ultrasound/laser therapy, prostatectomy, or prostatic enucleation.
  • Prior bilateral orchiectomy, planned long-term (>6 months duration) androgen suppression or peripheral androgen blockade, or chemotherapy or immunotherapy for prostate cancer.
  • Prior hemi- or total hip arthroplasty.
  • Diabetes mellitus associated with vascular ulcers or wound healing problems, ulcerative colitis, connective tissue disorder, or chronic (≥120 days) warfarin or clotting factor inhibitor (e.g., rivaroxaban) use planned.

  • Co-morbid severe concurrent disease which, in the judgment of the investigator, would result in life expectancy <5 years.

    • Patients with a left cardiac ventricular assist device are ineligible.
    • Patients with an implanted medical electronic device (e.g., cardiac pacemaker) remain eligible if device monitoring complies with standard of practice (e.g., Cardiology and Medical Physics evaluation, function checks and during-treatment monitoring).
  • Immunocompromised due to HIV positive state.
  • Medical or psychiatric conditions that preclude informed decision-making or adherence.

  • Prior registration to an Institutional Review Board-approved therapeutic research study that includes proton beam therapy or photon-based radiotherapy (e.g., randomization to proton beam therapy vs. photon-based radiotherapy).

    • Registration to a non-therapeutic (e.g., biomarker, medical physics) only research study is not an exclusion.
  • Inability to start radiation per protocol.

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

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
Adverse Events
Time Frame: 24 months
Will be assessed by the number of late grade ≥3 Gastrointestinal and Renal and Urinary/Genitourinary adverse event incidents recorded at 24 months after SABR
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
Biochemical (PSA) failure
Time Frame: 120 months
Assessed as time from registration until the date prostate-specific antigen value is ≥ prostate-specific antigen nadir + 2.0 ng/mL estimated by the Gray cumulative incidence method.
120 months
Overall survival
Time Frame: 120 months
Overall survival is defined as the length of time participants are alive after the start of treatment.
120 months
Quality of life - EPIC
Time Frame: Baseline; 120 months
ssessed as time from registration until the date prostate-specific antigen value is ≥ prostate-specific antigen nadir + 2.0 ng/mL estimated by the Gray cumulative incidence method.. The EPIC consists of 13 questions answered on varying 5-point scales (e.g., Very Poor/Non to Very Good or No Problem to Big Problem). Subdomains for urinary, bowel, and sexual function will be summarized descriptively. Changes across time will be evaluated to assess patient function and quality of life after study treatment.
Baseline; 120 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: Brad J. Stish, MD, 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.

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 12, 2017

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.
December 31, 2024

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.
December 31, 2024

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 17, 2017

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 17, 2017

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.
May 19, 2017

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.
February 25, 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.
February 23, 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.
February 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.
  • 17-000680
  • ROR1752 (Other Identifier: Mayo Clinic)
  • NCI-2024-01752 (Registry Identifier: CTRP (Clinical Trial Reporting Program))

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.

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