5500/20 Vs. SABR or Brachytherapy for PRimary OligoMetastatic Prostate Cancer Treatment (PROMPT)

We will investigate whether ultrahypofractionation using stereotactic ablative radiotherapy (SABR) or brachytherapy is as well-tolerated as moderately hypofractionated external beam radiotherapy (EBRT) for treating the prostate in patients with oligometastatic prostate cancer. Secondary aims include assessment of progression-free survival (PFS) and overall survival (OS) as well as cost-effectiveness. We hypothesize that ultrahypofractionation will maintain favorable toxicity profiles and quality of life while achieving comparable or better efficacy, thereby providing a convenient and cost-effective alternative to moderately hypofractionated EBRT.

Men newly diagnosed with low volume oligometastatic prostate cancer defined as fewer than 5 bone metastases and/or non regional lymph node involvement who agree to treatment of the primary cancer with radiation will be randomized between standard moderately hypofractionated external radiotherapy (5500 centiGray/20 fractions as per Stampede trial) and one of 3 alternatives: stereotactic body radiotherapy (SABR) to deliver 36 Gy/5 fractions, or low dose rate Iodine 125 permanent seed implant or a single high dose rate temporary implant. The trial will take place in 4 regional cancer centers of British Columbia Cancer Agency, with each center choosing their preferred alternative to 5500/20. To achieve 4 equally sized treatment arms, each randomization is weighted 3:1 for 42 patients in each arm and 168 total accrual. The primary endpoint is urinary quality of life as assessed by the International Prostate Symptom Score (IPSS) . As the typical acute symptoms from each of these radiation modalities has a unique time course, assessments are done at 6 different points during the first 2 years. Secondary endpoints are global quality of life as assessed by Expanded Prostate Cancer Index (EPIC) urinary, bowel and sexual scores, progression free survival, overall survival and cost effectiveness.

Eligibility Criteria:
Inclusion Criteria:

* Able to provide informed consent
* European Cooperative Oncology Group performance status 0 to 2
* Medically fit for all protocol treatment and follow-up
* Histologically confirmed adenocarcinoma of the prostate
* Newly diagnosed any Tumor stage, any Nodal stage but with oligo metastases
* No prior therapy for prostate cancer apart from androgen deprivation
* Able to complete the necessary investigations prior to randomization (History and physical examination, PSA)
* Able to complete the necessary investigations prior to start of Radiotherapy (Transrectal ultrasound-guided biopsy or equivalent, CT chest, abdomen \& pelvis or MRI abdomen and pelvis, and Bone scan)
* Planned for long-term androgen deprivation therapy (greater than 9 months in duration)

Exclusion Criteria:

* High metastatic burden defined as 5 or more bone metastases or visceral metastases
* Abnormal liver function
* Contraindications to EBRT such as active inflammatory bowel disease or previous pelvic radiation
* Medically unfit for anesthesia
* International Prostate Symptom Score (IPSS) greater than 20
* Restrictive flow pattern with peak flow rate less than10 mL per second or post-void residual greater than 25 per cent of voided volume (when uroflowmetry available)
* Prostate volume greater than 60cc after maximal cytoreduction
* Pubic arch interference
* Transurethral resection of prostate (TURP) within 12 weeks of brachytherapy