Related Experiment Videos
[Usefulness of free prostate specific antigen in the detection of prostate cancer]
G Azócar1, O Castillo, R Van Cauwelaert
1Unidad de Urología, Clínica Santa María. gazocar@rdc.cl
Background:
The predictive value of prostate specific antigen for prostate cancer, when levels are between 4 and 10 ng/ml, is low. Within these range of values, some authors recommend the measurement of the free fraction of the antigen to improve its predictive capacity.
Aim:
To evaluate the predictive value of the free fraction in subjects with prostate specific antigen values between 4 and 10 ng/ml.
Patients And Methods:
One hundred and forty subjects with prostate specific antigen between 4 and 10 ng/ml were evaluated. All were subjected to transcrectal ultrasound examination with biopsies and the free fraction of the antigen was measured by enzyme immuno assay.
Results:
Cancer was diagnosed in 36 subjects, all others had a benign prostatic hyperplasia. Mean prostate specific antigen values were 7.4 and 7.1 ng/ml in patients with cancer and hyperplasia, respectively. The percentage of free prostatic specific antigen was 9.8 and 19.8% in subjects with cancer and hyperplasia respectively (p < 0.001). Using receiver operating characteristic (ROC) curves, a free prostate specific antigen of 13% was the best cutoff value for predicting prostate cancer.
Conclusions:
In subjects with prostate specific values between 4 and 10 ng/ml, the measurement of the free fraction of this antigen can improve the predictive value of this parameter for the detection of prostate cancer.