Abstract: Two trials met the inclusion criteria. Both trials commenced prior to the widespread availability of prostate-specific antigen (PSA) screening; hence the results may not be applicable to men with PSA-detected disease. One trial (N = 142), conducted in the US, was judged to be of poor quality. All cause (overall) mortality was not significantly different between RP and WW groups after fifteen years of follow up (Hazard Ratio (HR) 0.9 (95% Confidence Interval (CI) 0.56 to 1.43). The second trial (N = 695), conducted in Scandinavia, was judged to be of good quality. After 12 years of follow up, the trial results were compatible with a beneficial effect of RP on the risks of overall mortality, prostate cancer mortality and distant metastases compared with WW but the precise magnitude of the effect is uncertain as indicated by the width of the confidence intervals for all estimates (risk difference (RD) -7.1% (95% CI -14.7 to 0.5); RD -5.4% (95% CI -11.1 to 0.2); RD -6.7% (95% CI -13.2 to -0.2), respectively). Compared to WW, RP increased the absolute risks of erectile dysfunction (RD 35% (95% CI 25 to 45)) and urinary leakage (RD 27% (95% CI 17 to 37)). These estimates must be interpreted cautiously as they are derived from data obtained from a self-administered questionnaire survey of a sample of the trial participants (N = 326), no baseline quality of life data were obtained and nerve-sparing surgery was not routinely performed on trial participants undergoing RP. The existing trials provide insufficient evidence to allow confident statements to be made about the relative beneficial and harmful effects of RP and WW for patients with localised prostate cancer. The results of ongoing trials should help to inform treatment decisions for men with screen-detected localised prostate cancer.

Plain-language summary: Two completed randomised controlled trials were identified. One trial was considered to be of good quality whilst the second trial was of poor quality. The two trials commenced prior to the widespread use of the prostate-specific antigen (PSA) blood test as a screening test for prostate cancer, and hence did not involve many men with PSA-detected cancers. Ongoing trials (PIVOT; ProtecT; START) will provide evidence of the comparative effects of RP and observation protocols for men with PSA-detected cancers. The one good quality trial included in this review involved men with cancers detected by methods other than screening who were randomly allocated to either RP or WW and followed up for 12 years. This single trial does not provide sufficient evidence to allow confident statements to be made about the magnitude of any beneficial and harmful effects of RP compared with WW for men with clinically detected prostate cancers. The trial results indicate that RP is likely to reduce the risks of overall mortality, prostate-cancer mortality and distant metastases (cancer spread) compared to WW, but the magnitude of the effect is unclear. Furthermore, the risk reductions appear to have been limited to men less than 65 years of age. This trial also provides evidence that RP increases the risks of erectile dysfunction and urinary leakage. However, because of the manner in which the data on adverse effects were collected in the trial, confident statements cannot be made about how frequently these adverse effects occur. In addition, nerve-sparing surgery, which has the potential to reduce these complications, was not routinely performed on participants in the trial. A shared approach to decision-making is required whereby patients and their healthcare providers openly discuss the patient's personal values, preferences, and the limitations of the available evidence on potential benefits and potential harms of these treatment options.