In the Netherlands, most men with prostate cancer (PCa) are treated with radical whole-gland treatment, i.e. prostatectomy or radiotherapy. The burden of complications such as incontinence and erectile dysfunction associated with radical treatment is considerable. A recent systematic review by our group has shown that focal therapy of PCa seems to reduce the burden of treatment side-effects in men with intermediate-risk disease, maintaining their quality of life without compromising oncological effectiveness. The costs of side effects that can be prevented are estimated at €5456 per patient, resulting in total expected cost savings of about €22 million per year in The Netherlands. Furthermore, exploration of the benefit-risk balance under patients showed that they are willing to sacrifice some survival for an improvement in quality of life (QoL). Focal therapy comprises a modern alternative to selectively treat a specific part of the prostate while preserving the rest of the gland. There is, however, a lack of high-quality evidence, and numerous papers therefore recommend to perform a multicenter randomized controlled trial (RCT). The RCT should have long-term follow-up, predefined assessment of cancer-specific and health-related QoL outcome measures, and economic evaluations to inform policymakers regarding cost-effectiveness. This RCT on focal therapy versus usual care is urgently needed to enable focal therapy to overgrow the experimental status, provide the evidence needed for guidelines, and make this available for selected patients who benefit from this strategy. Because of its promising results in other countries, focal therapy is increasingly requested by patients, but due to the lack of high-quality evidence, it is not reimbursed yet. This has been designated by both the PCa patient support group and physicians as a failure of both the market and the funding agencies. The investigators, therefore, aim to perform a high-quality multi-center RCT to provide the evidence needed to decide on reimbursement and implementation of focal therapy in patients with intermediate-risk, unilateral clinically localized PCa in the Netherlands.