Two-session MRI-guided proton treatment for low- and intermediate-risk prostate cancer

2-fraction Stereotactic Body Proton Therapy (SBPT) With Magnetic Resonance Imaging (MRI) Guidance in Localized Prostate Cancer: A Single-arm Phase II Non-randomized Trial

This project tests whether two MRI-guided proton therapy sessions can safely and effectively treat adult men with low- or intermediate-risk prostate cancer instead of the usual five sessions.

Quick facts

• Phase: NA
• Study type: Interventional
• Enrollment: 35 (estimated)
• Sex: Male
• Sponsor: Hong Kong Sanatorium & Hospital (industry)
• Drugs / interventions: chemotherapy, radiation
• Locations: 1 site (Hong Kong)
• Trial ID: NCT07130682 on ClinicalTrials.gov

What this trial studies

The trial delivers two high-precision, MRI-guided stereotactic body proton therapy (SBPT) fractions with real-time on-board tumor tracking to men with low- or intermediate-risk prostate cancer. The goal is to match the safety and cancer-control outcomes of the standard five-fraction SBPT while reducing the number of treatment visits. Investigators will collect clinician- and patient-reported outcomes, including EPIC questionnaires, and monitor acute and late toxicity. Key exclusions include prior pelvic radiotherapy or prostate surgery, large prostate volume, hip replacements, MRI contraindications, and metastatic disease.

Who should consider this trial

Good fit: Adult men (≥18) with NCCN-defined low- or intermediate-risk prostate cancer who can undergo MRI, have ECOG performance status <2, and meet prostate-size and imaging criteria are the intended participants.

Not a fit: Men with prior pelvic radiotherapy or prostate-directed surgery, inflammatory bowel disease, prostate volume >100 cc, unilateral or bilateral hip replacements, MRI contraindications, or nodal/distant metastases are unlikely to benefit from this protocol.

Why it matters

Potential benefit: If successful, this approach could reduce the number of treatment visits and overall cost while maintaining similar side effects and cancer control to the five-session course.

How similar studies have performed: Ultra-short (2–5 fraction) X-ray SBRT for prostate cancer has shown excellent control and manageable toxicity, but two-fraction proton therapy with MRI guidance is relatively novel and has limited published evidence to date.

Eligibility criteria

Inclusion Criteria:

* Men aged \< 18 years with histologically confirmed low- or intermediate-risk prostate cancer per NCCN guidelines
* Eastern Cooperative Oncology Group (ECOG) performance status \<2
* Ability to undergo magnetic resonance imaging (MRI) simulation scans without absolute contraindications, such as cardiac implantable electronic devices
* Ability to complete the Expanded Prostate Cancer Index Composite (EPIC) questionnaire

Exclusion Criteria:

* History of inflammatory bowel disease or other cancers (except prostate cancer)
* Prior pelvic radiotherapy, chemotherapy, radical prostatectomy, cryosurgery, or focal therapy (e.g. high-intensity focused ultrasound \[HIFU\]) for prostate cancer
* History of bladder neck or urethral stricture
* Transurethral resection of the prostate (TURP) \< 8 weeks prior to SBPT
* Prostate volume \> 100cc on MRI
* Unilateral or bilateral hip replacements
* Nodal or distant metastases, as indicated by computed tomography (CT), MRI, or prostate-specific membrane antigen (PSMA) positron emission tomography (PET) scans
* Previous androgen deprivation therapy (ADT) lasting more than 6 months

Where this trial is running

Hong Kong

• Hong Kong Sanatorium and Hospital — Hong Kong, Hong Kong (RECRUITING)

Study contacts

• Study coordinator: Oi Lei Wong, Ph.D.

Conditions: Prostate Cancer Patients Treated by Radiotherapy, Proton Therapy, Clinician reported outcome, patient reported outcome, low or intermediate risk prostate cancer