ABSTRACT
The ultrasensitive PSA assay has been recently acknowledged as a useful tool for the monitoring of patients prostatectomized for prostatic cancer. We have evaluated a commercially available ultrasensitive PSA assay (Immulite Third Generation PSA-DPC-Los Angeles CA) in comparison with the routinely used PSA (Immulite PSA-DPC-Los Angeles CA). When evaluated with different approaches, the analytical sensitivity of ultrasensitive PSA ranged between 0.0029 and 0.0038 ng/ml. The biological detection limit was 0.0098 ng/ml. Dilution of samples with low PSA levels showed a good recovery (from 88 to 113%) up to 1:128 dilution factor (final PSA levels ranging from 0.004 to 0.016 ng/ml in different samples). The assay precision was excellent in the low dose range, the highest interassay interadjustment CV among replicates being 5.84% when assaying serum samples with PSA lower than 1.0 ng/ml. Besides its role in the follow-up of prostatectomized patients, the evaluated ultrasensitive PSA could be reliably used for the detection of clinically meaningful PSA variations in the low dose range, and it could therefore be a candidate for the assessment of PSA velocity.
Subject(s)
Prostate-Specific Antigen/blood , Prostatic Neoplasms/diagnosis , Aged , Aged, 80 and over , Humans , Male , Monitoring, Physiologic , Prostatectomy , Prostatic Neoplasms/blood , Prostatic Neoplasms/surgery , Reagent Kits, Diagnostic , Regression Analysis , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
Tissue polypeptide antigen, measured by both a polyclonal antibody (TPA IRMA Prolifigen) and a monoclonal antibody prototype kit (TPA-M IRMA Prolifigen), and the tissue polypeptide specific antigen were evaluated. The markers were measured in 266 serum samples and in 291 tumour cytosols from patients with primary breast cancer. The three markers were available in matched pairs of both serum and cytosol from the same patient in 144 cases. Diagnostic sensitivity of serum levels of the three markers was not significantly different when using cut-off values calculated on the basis of healthy subjects. In the cytosol, tissue polypeptide antigen (TPA IRMA), tissue polypeptide antigen (TPA-M IRMA) and tissue polypeptide specific antigen were significantly correlated with steroid receptor status, while their serum levels were not. Cytosol and serum levels of the three markers were not significantly associated. All three were significantly correlated both in serum and in cytosol. The association was closer between tissue polypeptide antigen (TPA IRMA) and tissue polypeptide antigen (TPA-M IRMA) than between each of these two markers and tissue polypeptide specific antigen. From these findings we draw the following conclusions: 1. Tissue polypeptide specific antigen (TPA IRMA) and tissue polypeptide antigen (TPA-M IRMA) probably provide superimposable information both in serum and in cytosol; 2. Tissue polypeptide specific antigen and tissue polypeptide antigen (TPA IRMA) or tissue polypeptide antigen (TPA-M IRMA), although closely associated, probably measure in part different cytokeratins. Therefore, they should not be considered interchangeable in individual patients; 3. The determination of the markers in serum and in cytosol provides different information concerning the tumour phenotype.
