Feasibility Trial Of Image Guided External Beam Radiotherapy With Or Without High Dose Rate Brachytherapy Boost In Men With Intermediate-Risk Prostate Cancer

Inclusion Criteria: * Histologically confirmed prostate adenocarcinoma. The date of the last biopsy that verifies that the eligibility criterions have been met must be within 9 months prior to randomization. There must be no prior treatment. * Intermediate-risk cancer patients based on the NCCN Guidelines (www.nccn.org): • TNM classification: * T2b-T2c and Gleason Score \< 8/10 and PSA \< 20 ng/ml; or * T1c-T2a and Gleason Score 7/10 and PSA \< 20 ng/ml; or * T1c-T2a and Gleason Score ≤ 6/10 and 10 ≤ PSA \< 20 ng/ml For patients who have been on alpha reductase inhibitors within the last 6 months, use the following guidelines: * T2b-T2c and Gleason Score \< 8/10 and PSA ≤ 10 ng/ml; or * T1c-T2a and Gleason Score 7/10 and PSA ≤ 10 ng/ml; or * T1c-T2a and Gleason Score ≤ 6/10 and 5 ≤ PSA ≤ 10 ng/ml * No alpha reductase inhibitors (i.e. avodart, proscar) use within 2 weeks of randomization. A washout period of 2 weeks is required prior to randomization. * Prostate volume ≤ 75 cc. * American Urological Association (AUA) Symptom Index score \< 20. * Judged to be medically fit for IGRT and HDR brachytherapy boost by a radiation oncologist. * ECOG Performance Status of 0 or 1. * ≥ 18 years of age. * Patient consent must be appropriately obtained in accordance with applicable local and regulatory requirements. Each patient must sign a consent form prior to enrolment in the trial to document their willingness to participate. * Patients must be accessible for treatment and follow-up. Patients registered on this trial must be treated and followed at the participating centre. This implies there must be reasonable geographical limits (for example: 1 ½ hour's driving distance) placed on patients being considered for this trial. Investigators must assure themselves the patients registered on this trial will be available for complete documentation of the treatment, adverse events, and follow-up. * Protocol treatment is to begin within 4 weeks of patient randomization. HDR brachytherapy boost treatment is to begin within 3 weeks before or after IGRT for those randomized to Arm 2. * Participants must be willing to take precautions to prevent pregnancy while on treatment. In addition to routine contraceptive methods, "effective contraception" also includes heterosexual celibacy and surgery intended to prevent pregnancy (or with a side-effect of pregnancy prevention). However, if at any point a previously celibate patient chooses to become heterosexually active during the time period for use of contraceptive measures, he is responsible for beginning contraceptive measures. Exclusion Criteria: * History of transurethral resection of the prostate (TURP). * Patients with a history of other malignancies, except: adequately treated non-melanoma skin cancer, or other solid tumours curatively treated with no evidence of disease for ≥ 5 years. * Prior or current bleeding diathesis. * Prior pelvic or prostate radiotherapy. * Previous history of (or planned) androgen deprivation therapy. * Evidence of metastatic disease. * Any serious active disease or co-morbid medical condition, laboratory abnormality, psychiatric illness, active or uncontrolled infections, or serious illnesses or medical conditions that would prevent the patient from participating or to be managed according to the protocol (according to investigator's decision).