The PCA3 test is a new type of test that may help to diagnose prostate cancer.
PCA3 is short for Prostate CAncer gene 3. Prostate cells have PCA3 genes that make the cell produce a small amount of a particular protein. Prostate cancer cells make much more of this protein than normal cells. When the level of PCA3 protein is high, it leaks into the urine.
Researchers have been checking whether they can use PCA3 protein to diagnose prostate cancer. The company who make the test have sent out a lot of publicity about it. But we don’t yet know exactly how well the test may work.
Research into PCA3
The early research into PCA3 looks quite promising. But we need more research to find exactly how much PCA3 in the urine is a sign of prostate cancer. The PCA3 test isn’t yet accurate enough to be used on its own as a test for prostate cancer. It is more likely to be used as well as a PSA test, to help your doctor decide whether you need a prostate biopsy.
A study in America in 2006 compared the PCA3 urine test with the PSA blood test to find out which was better at diagnosing prostate cancer. The PCA3 level in urine was more accurate at picking up prostate cancer than the PSA level in the blood.
In early 2007, Dutch researchers published the results of another trial. Doctors did PCA3 urine tests on men with raised PSA levels. The doctors found using both tests helped them to decide which men needed a prostate biopsy.
How you have the PCA3 test
The test is in two parts; a rectal examination, and a urine test.
You need to have a rectal examination because this massages the prostate gland and helps the PCA3 to go into the urine. You then have to give the urine sample straight after the rectal examination, and you normally get the results within a few days.
The PCA3 test is not available through the NHS at the moment as it is still experimental. It is available in a few private hospitals and clinics. The cost is between £300 and £400. You could talk to your doctor about whether it is an option for you.
Research into other new tests
In October 2006 the Institute of Cancer Research launched a new website to further the development of prostate cancer screening.
Aimed at the public, patients, family members and healthcare professionals, it contains information about IMPACT (part funded by ourselves), an international screening study, targeted at men with a genetic predisposition to prostate cancer.
The IMPACT website also contains general information on prostate cancer, screening and genetics.
What is IMPACT?
IMPACT stands for Identification of Men with a genetic predisposition to ProstAte Cancer: Targeted Screening in BRCA1/2 mutation carriers and controls. Current research suggests that men with mutations in the BRCA1 and BRCA2 genes have an increased risk of developing prostate cancer.
The IMPACT study is being led by Dr Rosalind Eeles, Team Leader in Translational Cancer Genetics.
Since its introduction in the 1980s the prostate-specific antigen (PSA) test has become the backbone of prostate cancer screening, but it has also caused a high level of controversy.
A large proportion of men who are diagnosed with prostate cancer never actually experience any clinical symptoms or a reduction in lifespan as a result of this disease.
A major problem with the PSA test is its inability to differentiate between aggressive and clinically insignificant forms of prostate cancer.
The IMPACT study will evaluate whether the PSA test can improve early detection of disease in men who carry BRCA1/BRCA2 mutations.
IMPACT will also be collecting additional urine and blood samples to facilitate the development of a more reliable screening protocol for prostate cancer.