Comparison Between a New PSA Assay With the Well‐Established Beckman Coulter Immunoassay: A Preliminary Report

Prostate-specific antigen (PSA) is a critical biomarker for prostate cancer (PCa) patient clinical management. In this study, we sought to compare three different immunoassays (CLIA): Beckman Coulter Access Hybritech (PSA-B) (reference method), Immulite 2000 PSA (PSA-I) and the newly introduced Atellica IM PSA assay (PSA-A). We selected serum samples from our routine clinical testing at University Hospital Federico II between April and May 2024 from 104 men with a median age of 66 years (interquartile range = 57-74). Total PSA was determined using three different assays: PSA-B, PSA-A and PSA-I. A significant correlation between PSA-B and PSA-I assays was found for samples in the overall population (Spearman <i>r</i> (<i>ρ</i>) = 0.99, <i>p</i> < 0.0001). PSA-I displayed a strong correlation with PSA-B for values below 2 ng/mL (<i>ρ</i> = 0.98, <i>p</i> < 0.0001), for values between 2 and 10 ng/mL (<i>ρ</i> = 0.97, <i>p</i> < 0.0001) and for values above 10 ng/mL (<i>ρ</i> = 0.77, <i>p</i> < 0.0001). A significant positive correlation was found between PSA-B and PSA-A in the overall population (<i>ρ</i> = 0.97, <i>p</i> < 0.0001) and in stratified analyses between PSA-A and PSA-B for values below 2 ng/mL (<i>ρ</i> = 0.86, <i>p</i> < 0.0001), from 2 ng/mL to 10 ng/mL (<i>ρ</i> = 0.93, <i>p</i> < 0.0001) and above 10 ng/mL (<i>ρ</i> = 0.77, <i>p</i> < 0.0001). Although both PSA-I and PSA-A demonstrated a significant positive correlation with PSA-B, PSA-I displayed a significantly better correlation with PSA-B than PSA-A in samples with PSA below 2 ng/mL.