Proton-Based Stereotactic Ablative Body Radiotherapy for Prostate Cancer


About this study

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.

Patients undergo evaluation and medical care in the same way that they would if they were not part of this trial. This may include standard of care blood tests (for example, PSA) and scans (for example, MRI). Five SABR treatments will be given with proton beam therapy over two weeks, with up to two treatments each week. Participants will complete a quality-of life questionnaire before starting SABR, at the end of SABR, at three, six and 12 months after SABR, and then yearly.

Participation eligibility

Participant eligibility includes age, gender, type and stage of disease, and previous treatments or health concerns. Guidelines differ from study to study, and identify who can or cannot participate. There is no guarantee that every individual who qualifies and wants to participate in a trial will be enrolled. Contact the study team to discuss study eligibility and potential participation.

Inclusion Criteria:

  • Male, age ≥ 18 years.
  • Histological confirmation of adenocarcinoma of prostatic origin.
  • AJCC 7th edition clinical T1b-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.

Participating Mayo Clinic locations

Study statuses change often. Please contact the study team for the most up-to-date information regarding possible participation.

Mayo Clinic Location Status Contact

Rochester, Minn.

Mayo Clinic principal investigator

Thomas Pisansky, M.D.

Closed for enrollment

Contact information:

Adam Amundson


More information


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