Prospective Evaluation of Proclarix® Test to Improve Risk Stratification in Men Scheduled for MpMRI and Prostate Biopsy in Cantonal Hospital Aarau

The use of prostate-specific antigen (PSA) for the screening of prostate cancer has led to higher detection rates and a shift to lower and therefore potentially more curative disease stages at diagnosis and thus subsequently to a lower mortality. A suspicious digital rectal examination of the prostate or an increased PSA value are suspicious for PCa and indicate a confirmatory prostate biopsy . Almost 25% of all men report moderate to severe pain after the biopsy. Serious complications such as urosepsis requiring intensive medical monitoring are less common. There are also other predictors for the presence of prostate cancer: including positive family history in first-degree relatives, low PSA-ratio (= ratio between free to total PSA), older age and African-American race. In order to reduce the number of unnecessary prostate biopsies, numerous prostate-cancer risk calculators based on these predictors have been designed. Risk-calculators serve as an aid to clinical decision-making. For example, if the calculated risk of prostate cancer is low, a PSA follow-up can be a viable alternative to prostate biopsy. However, these risk calculators often have some shortcomings. The two most frequently used calculators are based on cohorts of men in whom the biopsies were performed as part of a study protocol regardless of the clinical context. These cohorts do not realistically represent the collective of patients to whom a prostate biopsy is indicated. Furthermore, the cohorts of these calculators are mostly very old and do not take into account the technical developments with improved sensitivity/specificity in recent years. Nowadays, a multiparametric magnetic resonance imaging (mpMRI) of the prostate is being performed and suspicious areas in the prostate are explicitly targeted, leading to an improved detection of significant carcinoma.The possibility of determining novel laboratory predictors such as biomarkers has been lately under investigation. All of these biomarkers are not included in the currently available risk calculators or are poorly validated. A pathological grading system, the so-called Gleason score, is a pathological grading system differentiating between less versus more aggressive prostate cancer cells. The most frequently used risk calculators have been developed based on patient cohorts that were created at a time before the Gleason score was revised to its current status. Thus, many previously low-grade carcinomas would be classified as more aggressive ones according to current pathology guidelines. Based on these circumstances, the development of a new PCa risk stratification models is of major clinical importance. In addition, as all biomarker measurements rely heavily on analytical performance of laboratory equipment, the quality assurance is an important factor and should be under scrutiny, especially when new biomarkers are under investigation.

Proclarix is a CE-marked test based on two new biomarkers, Thrombospondin 1 (THBS1) and Cathepsin D (CTSD), combined with PSA values and the patient's age. A software algorithm returns a risk assessment that can be utilized to predict clinically significant PCa (ISUP group 2 or higher).