Annals of Clinical Biochemistry > Volume 45, Number 3 > Pp. 270-274

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Eekers, D. B. P. Articles by ten Kate, J. PubMed PubMed Citation Social Bookmarking                      What's this?

Original Articles

Why determine only the total prostate-specific antigen, if the free-to-total ratio contains the information?

Daniëlle Berty Petra Eekers¹, Andrea Laschet², Monique de Groot³, Erik Roelofs⁴, Arnold Kester⁵, Karl Delaere⁶, Philippe Lambin⁴, Francis van Gils⁴, Marius Nap⁷ and Joop ten Kate⁸

¹ Dr Bernard Verbeeten Institute, Tilburg, The Netherlands; ² Department of Clinical Chemistry, Atrium Medical Centre, Heerlen, The Netherlands; ³ Department of Clinical Chemistry, Amphia Hospital, Breda, The Netherlands; ⁴ Maastricht Radiation Oncology, Maastricht, The Netherlands; ⁵ Department of Methodology and Statistics, Maastricht University, Maastricht, The Netherlands; ⁶ Department of Urology; ⁷ Department of Pathology, Atrium Medical Centre, Heerlen, The Netherlands; ⁸ Department of Clinical Chemistry, Maasland Hospital, Sittard, The Netherlands

Corresponding author: Dr Daniëlle Berty Petra Eekers. Email: eekers.d{at}bvi.nl

Background: Total prostate-specific antigen (tPSA) is the best available test for the detection of prostate cancer but it lacks specificity. The free-to-total ratio (F/T ratio) is used to increase specificity in the range of tPSA of 4–10 µg/L.

Materials and methods: Four hundred and seven biopsy results and quantitative tPSA and F/T ratio data were combined. Using the histological determination, normal/hyperplasia versus malignant as a gold standard, receiver operating characteristic (ROC) curves as well as the areas under the curve (AUC) for tPSA and F/T ratio were determined. The differences between the two AUCs were considered for various tPSA ranges and specificities of F/T ratio and tPSA were calculated.

Results: In the total group, there was a gain of specificity of 11% (from 23% to 34%) when the sensitivity was 92% (using a cut-off >0.28 for the F/T ratio and a cut-off >4 µg/L for tPSA). When considering the group of patients for which the F/T ratio is currently used (4–10 µg/L), the gain of specificity was 27% (from 2% to 29%). This implicates that the number of unnecessary biopsies taken will be reduced by 27%. Moreover, the AUC of the F/T ratio was significantly higher at an even broader range of tPSA, i.e. up to 40 µg/L.

Conclusions: This study demonstrates that the F/T ratio has better diagnostic performance than tPSA, not only in the grey zone of tPSA, but also outside the grey zone, i.e. up to 40 µg/L.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?