From PSA to Stockholm3: Study Part 1

Background: Prostate cancer constitutes about 15 % of new cases of cancer among men globally, but about 27 % of all new cases of cancer in men in Norway. It is also the leading cause of cancer death among men, and nearly 1100 Norwegian men died from prostate cancer in 2014. However, only about 30 percent of new cases have an aggressive form of the disease. Therefore, the challenge is to detect and distinguish patients with aggressive disease from patients who have a low risk cancer. The Prostate-Specific Antigen (PSA) is currently the main test used in primary care to detect and prioritize patients for further diagnostics. PSA is used for screening in many countries, but the Norwegian authorities consider the harms of using PSA for screening purposes (over-diagnosis and overtreatment) to outweigh the benefits (potentially reduced mortality). Nevertheless, it has been documented that a substantial amount of opportunistic PSA screening takes place in Norway. At present, a novel test called the Stockholm3 test has been developed. A large prospective study has shown that the efficacy of the Stockholm3 test is superior to PSA, and both the sensitivity and the specificity are substantially higher for Stockholm3 than for PSA. Aim The aim of this study is to analyze the effectiveness of the Stockholm3 test in regular clinical practice, including both primary care and specialized health care. Study Design From September 2017, the urological department at Stavanger University Hospital requires a Stockholm3 answer in referrals of patients for further diagnostics of possible prostate cancer. Comparable clinical data will be collected for a period before - and from a corresponding period after the Stockholm3 test was taken into use. An analysis will then be carried out where the results from the period where referrals were based primarily on PSA will be compared with the results for the period in which the Stockholm 3 test was used. Power calculation Based on results from the original Stockholm3 study and aggregated figures regarding PSA testing, prostate biopsies and MRI of the prostate in Stockholm and Stavanger, a statistical power has been calculated. Based on a two-sided alpha at 0.05 (i.e., 5%) and a 90% power the study need about 8000 participants to reliably answer the main study questions. An interim analysis will be conducted in the inclusion phase. A new power calculation will be performed based on the registered data, and the need of participants will be adjusted if necessary.