In the area of prostate cancer diagnoses, the ultimate goal is to find methods which would reveal whether a man has prostate cancer or is cancer-free, and if cancer is detected, is it aggressive requiring treatment or slow-growing requiring only monitoring. Many of these tests utilize biomarkers, substances like prostate-specific antigen (PSA) measured in a body fluid. While much data is available on the use of PSA, published studies on newer tests is very limited. Such tests can also be marketed without proof of benefit and may contain unsubstantiated claims. Given these limitations, here are some tests that are commercially available. Your personal physician should be consulted first and foremost. Costs and insurance coverages vary greatly. Insurance carriers and test manufacturers should be contacted for further information and possible assistance.
In addition to PSA, two tests that could help to decide whether a biopsy is necessary include the Prostate Health Index (phi test) and the 4Kscore. The phi test measures blood levels of PSA, free PSA and a precursor of PSA called pro-PSA or p2PSA. The phi test combines all three measurements mathematically to better determine whether prostate cancer is present. The phi test results (scaled from zero to 55 and above) reflect the probability that a biopsy will detect cancer. Research suggests that pro-PSA levels are a better indicator of prostate cancer than total or free PSA levels. Men with elevated pro-PSA levels are at risk for a more aggressive form of cancer. The test is indicated for men 50 years and older who have negative digital rectal exams and PSA levels of 4-10 ng/mL. For additional information on the phi test and its availability, see the following link to Beckman Coulter Diagnostics. The 4Kscore is a blood test which measures levels of three variants of PSA (total, free and intact PSA) plus an enzyme called human kallikrein 2 (hK2) which is elevated in men with prostate cancer and may promote its growth and spread. The 4Kscore is slated to be released in the United States in 2014.
Other tests are available to help determine whether a repeat biopsy is necessary as some initial prostate biopsies are inconclusive or negative in high-risk men. Progensa is a urine test that detects the presence of a gene called prostate cancer antigen 3 (PCA3). This gene is over-expressed (more active) in 95% of men with prostate cancer but not in men with healthy or enlarged prostates. Progensa can be used in men over 50 who have had one or more negative biopsies but who may be deemed candidates for prostate cancer nonetheless. This test has been discussed on this website in blogs dated 3/26/2012, 7/16/2013, 10/8/2013 and 12/31/2013. ConfirmMDx is a test that analyzes the DNA methylation status of a man’s biopsied prostate tissue. DNA methylation is a biochemical process that “tags” specific parts of DNA (the building blocks of genes). The result of this process is that the activity of tumor suppressor genes is decreased or turned “off'”, thus facilitating cancer development. The Prostate Core Mitomic Test analyzes a man’s biopsied tissue looking for damage to mitochondrial DNA caused by cellular changes associated with prostate cancer. A negative test indicates a low risk for undiagnosed prostate cancer and repeat biopsies can be deferred.
If prostate cancer is detected, the big question is whether treatment is immediately required or could active surveillance be invoked. Is the tumor low-risk or aggressive? Gleason score and other information are currently used to provide these answers however several tests may also help. Prolaris is a test that uses a sample of biopsied tumor tissue to measure how rapidly cells are dividing. Prolaris scores range from -1.3 to + 4.7, with higher scores indicating a greater risk of dying from prostate cancer. Prolaris may also help to determine the risk of recurrence after a prostatectomy and to determine whether a man would benefit from additional therapies such radiation or hormone therapy. The Prolaris test has been described on this website in the April 12th, 2014 blog. The test called ProstaVysion analyzes biopsied tissue for the presence of two biomarkers. One is TMPRSS2:ERG, a fusion of two genes associated with the presence of prostate cancer. The other is PTEN, a gene that normally help suppress certain forms of cancer and is missing in 60% of men with metastatic prostate cancer. These two markers help provide a molecular analysis of prostate cancer aggressiveness and the patient’s long term prognosis. These genetic markers were also discussed in previous website blogs dated July 16, 2013, October 8th, 2013, December 31st, 2013 and January 4th, 2014. Thirdly, Oncotype DX examines the interactions between 17 genes in a biopsy sample to predict whether a tumor is likely to be aggressive. The resulting Genomic Prostate Score ranges from 0 to 100; a lower score suggests that the tumor is less likely to grow and spread while a higher score suggests a poorer prognosis and the need for immediate treatment. This test was also described previously in posts dated June 21, 2013 and January 10th, 2014. Finally, the NADiA ProsVue blood test measures the rate of tiny changes in PSA levels over time which can suggest the level of risk for recurrence for several years following a prostatectomy.
More specific information can be found in an article written by Dr. H. Ballentine Carter, Director of Adult Urology at Johns Hopkins in the May, 2014 issue of the Johns Hopkins Medicine Health After 50. One can subscribe to receive this periodical from Johns Hopkins for a fee.