MICRO-ultrasound Guided Prostate SBRT

Prostate cancer is one of the most common cancers in men, and many patients receive a treatment called external beam radiation therapy. This treatment usually works well, but in some men the cancer can return. Giving a higher dose of radiation to the whole prostate could lower this risk, but doing so can also cause more side effects to the bladder and bowel. Researchers have learned that cancer often comes back in specific spots inside the prostate called dominant intraprostatic lesions (DILs). If doctors can clearly see these areas, they may be able to safely give extra radiation just to those spots. A new type of imaging, called microultrasound (microUS), creates very detailed pictures of the prostate and may help doctors more accurately find these cancer areas.

This study will test whether it is safe and effective to use stereotactic body radiation therapy (SBRT)-a short, targeted form of radiation-together with a microUS-guided radiation boost to the cancerous spots inside the prostate. Researchers will compare treatment plans that use microUS to plans created using the current standard method, which relies on MRI images. By learning whether microUS can successfully guide targeted radiation, this research may help make advanced and more personalized prostate cancer treatment available to more patients.

Inclusion criteria

• Histologically confirmed carcinoma of the prostate (biopsy results with 12 months of enrollment)
• Intermediate risk as defined by NCCN criteria
• Conventional imaging (bone scan and abdominal pelvic computed tomography) is mandatory for NCCN unfavourable intermediate risk prostate cancer patients with PSA > 10. Negative nodal, skeletal or visceral metastases within 16 weeks of enrollment (for patients requiring staging). Alternatively, patients with no signs of extra-prostatic disease on PSMA-PET scans are also candidates for this trial
• ECOG performance status 0-1
• Willing to give informed consent to participate in this clinical trial
• Able and willing to complete QOL questionnaires Most responsive physician definition if androgen deprivation therapy will be used (only allowed for NCCN unfavourable intermediate risk prostate cancer)

Exclusion criteria

• Estimated prostate volume > 60cc (volume based on transrectal ultrasound)
• Prior TURP
• Prior prostate cancer treatment, including 5-alpha reductase inhibitor treatment
• Low, high or very high-risk disease as per NCCN guidelines
• Connective tissue disease or inflammatory bowel disease
• Contraindication to prostate microUS
• Men with double hip prostheses
• Contraindication for MRI (i.e. non-compatible stent, pacemaker, prosthesis etc.)
• Anticoagulation medication (if unsafe to discontinue for fiducial marker insertion)
• Diagnosis of bleeding diathesis