Screening Out Controversy...

To test or not to test? The controversy over prostate-specific antigen (PSA) screening is well known, with proponents of the test touting its potential to save lives and adversaries highlighting its risks (1). But this debate centers on the PSA test itself, rather than on prostate cancer screening – it’s simply that, for many years, no better or simpler test was available. Now, researchers from Sweden’s Karolinska Institutet may have an alternative to offer: the Stockholm 3 (STHLM3) model, a blood test designed to not only detect prostate cancer, but distinguish between low- and high-risk forms to prevent harmful overtreatment.

“PSA cannot distinguish between aggressive and benign cancer,” says Henrik Grönberg, the study’s principal investigator. “This leads to men who don’t have cancer, or who have a form that doesn’t need treating, going through an unnecessary, painful, and sometimes dangerous course of treatment. On top of this, PSA misses many aggressive cancers. Therefore, a more precise test than PSA is needed.” The STHLM3 model, which analyzes a combination of six protein markers, over 200 genetic markers, and clinical variables, is intended to provide a comprehensive risk estimate for aggressive cancers. In a prospective, population-based, paired, screen-positive, diagnostic study of men aged 50 to 69, he and his colleagues compared the performances of PSA tests and the STHLM3 model in detecting clinically significant prostate cancers (2). The infographic summarizes their key findings.

“Based on the STHLM3 trial with 58,818 men [including the training cohort], we have shown that the STHLM3 test discovers aggressive cancer earlier than the PSA test and reduces the number of false positive tests and unnecessary biopsies,” says Grönberg. “There has been great interest in the STHLM3 test both in the scientific community and among general practitioners.” In Sweden, the new test will be available in clinical care from March onward, and the Swedish National Board of Health and Welfare will evaluate a national screening program later this year. Given the uncertainties that surround current screening for prostate cancer, practitioners may want to keep an eye on STHLM3!