This month the FDA approved the use of the PCA3 assay to aid in the diagnosis of prostate cancer. This is good news for patients with an elevated PSA (prostate specific antigen) blood test who are concerned about their risk of having prostate cancer. The PCA3 test is used on urine samples from men after a prostate exam has been performed. It measures the number of copies of a prostate cancer related gene, and compares it to the number of copies of the gene for PSA. Studies have shown that the use of this assay can help sort out who is at higher risk for prostate cancer. This can help patients and urologists decide who would likely benefit from a prostate biopsy.
The FDA specifically approved the PCA3 assay for men who have had a prior prostate biopsy and for whom a repeat biopsy would be recommended based on the current data. Using the PCA3 assay, men who have a high PSA test from other causes such as benign enlargement of the prostate, may be spared unnecessary repeat biopsies. The PCA3 test is more specific than the PSA blood test. In studies, a negative PCA3 test predicted a negative biopsy 90% of the time in men who had a prior negative biopsy.
I have been using the PCA3 assay for the last year or so and have found it very helpful. There is a lot of controversy surrounding the use of the PSA in the diagnosis and treatment of prostate cancer. The PCA3 assay is a helpful new tool in our toolbox. If you have more questions about PSA or PCA3 testing, speak with your health care provider.