The most frequently used
biomarker for prostate cancer today is the
serum level of
prostate-specific antigen (PSA), or derived measurements. However, since PSA is
prostate-specific but not
cancer-specific, it is an imperfect biomarker. For example, PSA can increase in older men with
benign prostatic hyperplasia. Several new biomarkers are being investigated to improve the diagnosis of prostate cancer. Some of these can be measured in
urine samples, and it is possible that a combination of several urinary biomarkers will replace PSA in the future. Compared to serum PSA, PCA3 has a lower
sensitivity but a higher
specificity and a better
positive and
negative predictive value. It is independent of prostate volume, whereas PSA is not. It should be measured in the first portion of urine after
prostate massage with
digital rectal examination. This means that it could be useful clinically for a patient for whom digital rectal examination and PSA suggest possible prostate cancer, but the first prostate biopsy returns a normal result. This occurs in approximately 60% of cases, and on repeat testing, 20-40% have an abnormal biopsy result. Other uses that are being studied for PCA3 include its correlation with adverse tumor features such as tumor volume,
grading (
Gleason score) or extracapsular extension. These studies have so far produced conflicting results. ==Society and culture==