A systematic review of radiation therapy trials in prostate cancer has been performed according to principles adopted by the Swedish Council of Technology Assessment in Health Care (SBU). This synthesis of the literature is based on data from one meta-analysis, 30 randomized trials, many dealing with hormonal therapy, 55 prospective trials, and 210 retrospective studies. Totally the studies included 152,614 patients. There is a lack of properly controlled clinical trials in most important aspects of radiation therapy in prostate cancer. The conclusions reached can be summarized as follows: * There are no randomized studies that compare the outcome of surgery (radical prostatectomy) with either external beam radiotherapy or brachytherapy for patients with clinically localized low-risk prostate cancer. However, with the advent of widely accepted prognostic markers for prostate cancer (pre-treatment PSA, Gleason score, and T-stage), such comparisons have been made possible. There is substantial documentation from large single-institutional and multi-institutional series on patients with this disease category (PSA < 10, GS < or = 6, < or = T2b) showing that the outcome of external beam radiotherapy and brachytherapy is similar to those of surgery. * There is fairly strong evidence that patients with localized, intermediate risk, and high risk (pre-treatment PSA > or = 10 and/or GS > or = 7 and/or > T2) disease, i.e. patients normally not suited for surgery, benefit from higher than conventional total dose. No overall survival benefit has yet been shown. * Dose escalation to patients with intermediate-risk or high-risk disease can be performed with 3D conformal radiotherapy (photon or proton) boost, with Ir-192 high dose rate brachytherapy boost, or brachytherapy boost with permanent seed implantation. Despite an increased risk of urinary tract and/or rectal side effects, dose-escalated therapy can generally be safely delivered with all three techniques. * There is some evidence that 3D conformal radiotherapy results in reduced late rectal toxicity and acute anal toxicity compared with radiotherapy administered with non-conformal treatment volumes. * There is some evidence that postoperative external beam radiotherapy after radical prostatectomy in patients with pT3 disease prolongs biochemical disease-free survival and that the likelihood of achieving long-term DFS is higher when treatment is given in an adjuvant rather than a salvage setting. A breakpoint seems to exist around a PSA level of 1.0 ng/mL, above which the likelihood for eradication of the recurrence of cancer diminishes. * After prostatectomy, endocrine therapy prior to and during adjuvant radiotherapy may result in longer biochemical disease-free survival than if only adjuvant radiotherapy is given. No impact on overall survival has been shown. * There is fairly strong evidence that short-term endocrine therapy prior to and during radiotherapy results in increased disease-free survival, increased local control, reduced incidence of distant metastases, and reduced cause-specific mortality in patients with locally advanced disease. * There is some evidence that short-term endocrine therapy prior to and during radiotherapy results in increased overall survival in a subset (GS 2-6) of patients with locally advanced disease. * There is strong evidence that adjuvant endocrine treatment after curative radiotherapy results in improved local control, increased freedom from distant metastases, and increased disease-free survival in patients with loco-regionally advanced and/or high-risk disease. * There is moderately strong evidence that adjuvant endocrine treatment after radiotherapy results in longer overall survival compared with radiotherapy alone in patients with loco-regionally advanced disease.