Prostate Cancer - Treatment
Prostate cancer antigen 3 (PCA3, also referred to as DD3) is a gene which has noncoding messenger RNA that is overexpressed in prostate cancer. [1][2] This messenger RNA is useful as a tumor marker. [3]
Use as biomarker
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. [4]
Compared to serum PSA, PCA3 has a lower sensitivity but a higher specificity and a better positive and negative predictive value. [5] It is independent of prostate volume, whereas PSA is not. [6] It should be measured in the first portion of urine after prostate massage with digital rectal examination.[7]
PCA3 has been shown to be useful to predict the presence of malignancy in men undergoing repeat prostate biopsy.[7][8] This means that it could be useful in the clinical scenario in a patient in which 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% will have an abnormal biopsy result.[9]
Other uses that are being studies for PCA3 include its correlation with adverse tumor features such as tumor volume, grading (Gleason score) or extracapsular extension. These studies have thus far produces conflicting results. [10] [11] [12]
A commercial kit called the Progensa PCA3 test is marketed by the Californian company Gen-probe.[9] It is not available in the United States.[13]