Prostate specific antigen (PSA)-screening is an essential tool in identifying and treating prostate cancer, but it also has led to overtreatment of indolent conditions, Heather Lindsey writes in the August Clinical Laboratory News. Clinicians and researchers alike have been searching for improved screening methods to address PSA’s limitations. Imaging technologies also may fill in the gaps for PSA’s shortcomings, Lindsey writes.
Physicians already use variants of PSA to determine whether patients with elevated PSA levels need biopsies. Many clinicians however, have been looking to other biomarkers to provide more nuanced information on a patient’s cancer, thus avoiding the need for an invasive biopsy. Commercially available biomarker tests include Prostate Health Index (PHI), 4Kscore, SelectMDX, ExoDx Prostate, and Mi-Prostate Score. The National Comprehensive Cancer Network has included some of these tests in its prostate cancer screening recommendations.
Other up-and-coming laboratory screening test alternatives to PSA include the Stockholm 3 (STHLM3 model), which assesses plasma protein biomarkers PSA, free PSA, intact PSA—an uncleaved, enzymatically inactive form of PSA—human glandular kallikrein 2, microseminoprotein‐beta, and macrophage inhibitory cytokine-1.
The polygenic hazard score, can assess 54 single-nucleotide polymorphisms to determine patient risk of developing aggressive prostate cancer and age of onset.
There’s also the IsoPSA, which measures different PSA protein isoforms in serum tightly linked to prostate cancer by partitioning them with an aqueous two-phase solution. Data presented by Eric Klein, MD, chairman of the Glickman Urological and Kidney Institute at Cleveland Clinic in Cleveland at the American Urological Association annual meeting, indicated that IsoPSA could prevent half of all unnecessary biopsies, especially in combination with magnetic resonance imaging (MRI).
On the imaging front, multiparametric MRI, which provides a detailed view of the prostate and uses a scale of 1 to 5 to classify suspicious areas, prevented biopsies in 38% of patients who participated in one study. “Another study found that multiparametric MRI was better than PCA3 and PHI for identifying malignancy in men whose biopsies were negative but who were still suspected as having cancer,” writes Lindsey.
Pick up CLN’s August issue to learn more about the role of laboratories in prostate cancer screening, and how labs could help simplify the testing process.