Two RCTs, ERSPC21 and the Goteborg population-based prostate cancer screening trial (Goteborg-1),38 provide evidence that regular PSA screening every 2 to 4 years in patients aged 50 to 69 years reduces the risk of metastatic prostate cancer and prostate cancer mortality at 16 to 22 years, compared to no or opportunistic screening. The Goteborg-1 trial was designed separately from ERSPC with a separate power calculation and included patients 50 to 64 years of age.57 Patients aged 55 to 69 years were later included in ERSPC. The number needed to be screened (NNS, the inverse of the absolute risk reduction in prostate cancer mortality) and number needed to be diagnosed (NND, additional cases diagnosed) to prevent one death from prostate cancer depends on the screening protocol (including screening ages) and follow-up time (Table 3). <img src="images/Guidelines/Guideline%20Images/2026%20EDPC/2026%20EDPC-%20Table%203.png" alt="TABLE 3: Number Needed to Screen (NNS) and Additional Number Needed to Diagnose (NND) to Prevent One Death from Prostate Cancer by Study" title="TABLE 3: Number Needed to Screen (NNS) and Additional Number Needed to Diagnose (NND) to Prevent One Death from Prostate Cancer by Study" width="700" height="504" class="blockImg" /> A study comparing patients 60 years of age who have been screened every 2 years in the Goteborg-1 trial, compared to unscreened patients 60 years of age in the Malmö Preventive Project, showed that continuing to screen patients with PSA ≥ 2 ng/mL at 60 years of age had a favorable net-benefit in terms of reducing risk of prostate cancer metastasis and mortality at 15 years. At 15 years, the NNS to prevent 1 death from prostate cancer was 23 and NND was 6.60 The U.S. Prostate Lung Colorectal and Ovarian (PLCO) cancer screening trial was unable to demonstrate a statistically significant difference in prostate cancer mortality at 17 years of follow-up between patients randomized to screening versus usual care.61 However, the control group had a high degree of PSA testing (contamination) with more than 80% of patients receiving at least 1 PSA test during the trial.62 In later years, patients in the control groups of ERSPC and Goteborg-1 have also been exposed to PSA testing. In PLCO, the cut-off for biopsy was higher than in ERSPC (4 versus 3 ng/mL), the proportion of patients with elevated PSAs that were biopsied was lower (34% versus over 90%) and screening stopped after 6 years. Taking differences in implementation into account, a modeling study aiming to reconcile PLCO and ERSPC showed PSA screening versus no screening can reduce prostate cancer mortality by approximately 30% at 11 to 13 years.63 A modeling study primarily based on ERSPC compared the benefits and harms of annual PSA screening of patients aged 55 to 69 years. Over a life-time horizon with a PSA threshold of 3 ng/mL, screening would lead to 9 fewer deaths from prostate cancer for every 1,000 screened. The NNS to prevent one death from prostate cancer over a lifetime horizon was 98, and the NND was 5. Overall, screening was offset by a 23% reduction in quality-adjusted life years from life years gained, mainly owing to long-term side-effects from treatment.59 A U.S. model produced similarly low NND33 in evaluation of screening between ages 50 and 69 years using a PSA threshold of 4 ng/mL, which had been standard practice in the U.S. Again, SDM is highly recommended given the uncertainty involved in the PSA screening setting.