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

Moderate Versus Ultra Hypofractionation or Brachytherapy for PRimary OligoMetastatic Prostate Cancer Treatment

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.

Inclusion Criteria:

• Signed study specific informed consent
• European Cooperative Oncology Group performance status 0 to 2
• Histologically confirmed adenocarcinoma of the prostate
• Any Tumor stage, any T, any N, M1
• No prior therapy for prostate cancer apart from androgen deprivation
• Planned for long-term androgen deprivation therapy (greater than 9 months in duration)
• Patient is able and willing to complete the quality of life questionnaires, and other assessments that are a part of this study
• For brachytherapy arms, patient must be technically suitable for brachytherapy according to investigator, in terms of bladder function and prostate size.

Exclusion Criteria:

• High metastatic burden defined as 5 or more bone metastases or visceral metastases
• Contraindications to EBRT such as active inflammatory bowel disease or previous pelvic radiation
• For Brachytherapy Arms =: Any prior Transurethral resection of prostate