Post-prostatectomy SBRT with MRI/CT adaptive guidance to reduce urinary and bowel side effects

MAgnetic Resonance Imaging or Computed Tomography Guided Stereotactic Body Radiotherapy With Online Adaptive Technology for Minimizing Toxicity During Salvage or AdjUvaNt Radiotherapy for ProstatE Cancer (MASAMUNE)

Observational Jonsson Comprehensive Cancer Center · NCT07077239

This registry will try MRI- or CT-guided stereotactic body radiotherapy (SBRT), sometimes using on-table adaptive planning, for men after prostatectomy who have adverse pathology or a rising PSA.

Quick facts

Study typeObservational
Enrollment200 (estimated)
Ages18 Years and up
SexMale
SponsorJonsson Comprehensive Cancer Center Academic / other
Drugs / interventionsradiation
Locations1 site (Los Angeles, California)
Trial IDNCT07077239 on ClinicalTrials.gov

What this trial studies

This single-arm, prospective registry follows men treated with MRI- or CT-guided SBRT to the prostate bed with or without pelvic lymph node coverage, with adaptive treatments offered at clinician discretion. The study tracks patient-reported urinary and gastrointestinal quality of life up to 24 months after treatment. The target enrollment for patients receiving adaptive treatment is 200, with an expected accrual rate of about 40 patients per year, while there is no preset target for non-adaptive SBRT patients. Pelvic CT and MRI within 120 days are required for enrollment, though MRI exemptions are permitted for contraindications.

Who should consider this trial

Good fit: Ideal candidates are men who have had radical prostatectomy and now have adverse pathologic features, rising PSA, an intermediate/high Decipher score, or nodal involvement and who can undergo pelvic imaging and attend UCLA for treatment.

Not a fit: Men with widespread metastatic disease, those unable to access SBRT at the study site, or those with very low-risk post-operative findings are unlikely to receive benefit from this registry approach.

Why it matters

Potential benefit: If successful, this approach could reduce urinary and bowel side effects after postoperative radiotherapy while maintaining cancer control.

How similar studies have performed: Early reports of MRI-guided and adaptive SBRT in prostate and pelvic settings have shown promising reductions in toxicity, but prospective postoperative registry data remain limited.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria

* History of histologically confirmed, clinical localized adenocarcinoma of the prostate treated with radical prostatectomy with definitive intent.
* Presence of any ONE of the following:

  1. Adverse pathologic features at the time of prostatectomy (positive surgical margin, pathologic T-stage 3-4 disease, pathologic Gleason score 8-10 disease, OR presence of tertiary Gleason grade 5 disease)
  2. Documentation of rising prostate-specific antigen on at least two consecutive draws, with the magnitude of prostate-specific antigen exceeding 0.03 ng/mL
  3. Intermediate- or high-risk Decipher genomic classifier score
  4. Identification of prostate cancer in ≥1 lymph node at the time of prostatectomy (pN+ disease)
* CT scan and MRI of the pelvis within 120 days prior to enrollment \[note: (a) if patient has medical contraindication to MRI, an exemption will be granted and enrollment can proceed; (b) for patients with PSA \<1.0 ng/mL, the treatment planning CT can substitute for a diagnostic CT scan; (c) a low-field, radiation planning MRI can replace the diagnostic MRI if the patient refuses or cannot obtain a high-field MRI\].
* Bone scan OR advanced nuclear imaging study within 120 days prior to enrollment for patients with PSA \>1.0 ng/mL.
* Age ≥ 18.

  \~. KPS ≥ 70 and/or ECOG \<2.
* Ability to understand, and willingness to sign, the written informed consent

Exclusion Criteria

* Patients with any evidence of distant metastases. Note, evidence of lymphadenopathy below the level of the renal arteries can be deemed loco regional per the discretion of the investigator.

  * Patients with neuroendocrine or small cell carcinoma of the prostate
  * Prior pelvic radiotherapy
* History of Crohn's Disease, Ulcerative Colitis, or Ataxia Telangiectasia

Where this trial is running

Los Angeles, California

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Prostate Cancerprostatectomy
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.