A single high dose rate brachytherapy (HDR) treatment combined with a short course of external beam radiotherapy (EBRT) is a highly effective and well tolerated treatment for men with intermediate risk prostate cancer. High cancer control rates have also been reported with HDR used on its own, without the EBRT. The challenge has been to determine what HDR dose to use with a move towards one or two fractions by several investigators. These schedules are reported to be well tolerated in the short term, but with little long term data. The objective of this study is to investigate HDR monotherapy given as either one fraction of 19 Gy or two fractions of 13.5 Gy in a randomized phase II clinical trial. The primary endpoint is patient reported toxicity and health related quality of life at 1 year, and efficacy data will be also be analyzed. Sample size for the study is 174 patients, which we expect to accrue within 18 months.

Inclusion Criteria:

• histologically confirmed diagnosis of adenocarcinoma of the prostate
• low and intermediate risk disease defined as either Gleason 6 or Gleason 7 and PSA < 20ng/mL. PSA to be drawn within 60 days of registration
• prostate volume < 60 cc as determined by ultrasound, CT or MRI
• willing to give informed consent ot participate in this clinical trial
• able and willing to complete Expanded Prostate Index Composite (EPIC) questionnaire

Exclusion Criteria:

• documented nodal or distant metastases
• previous pelvic radiotherapy
• previous trans-urethral resection of prostate, previous prostatectomy or Highly Focused Ultrasound (HIFU)
• use of androgen deprivation therapy. Use of 5-alpha reductase inhibitors is permitted
• poor baseline urinary function defined as radiotherapy eg. connective tissue disease or inflammatory bowel disease
• significant medical co-morbidity rendering patient unsuitable for general anaesthetic