5500/20 vs. sabr or brachytherapy for primary oligometastatic prostate cancer treatment (prompt)

Conditions: Oligometastatic Prostate Cancer

Summary: 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

Keywords: prostate adenocarcinoma oligometastases radiotherapy hypofractionation brachytherapy