Elevated PSA and 4K Scores

[lenihant]

I have read that a PSA score above 4 ng/ml is considered in the elevated range and could be cause for prostate cancer concern. The PSA score has had some controversy associated with it and for a period of time my GP (in the States) recommended not to have it done. There is a newer test called the 4K Score which is still considered experimental in some parts of the world. After reading about these tests, I have a few questions I hope you help me with.

1. A PSA greater than 4 ng/ml is considered in the “elevated” range and has a probability of 15% that prostate cancer will be found if a biopsy is performed. Another factor that helps in the interpretation of this score is the amount of “Free PSA” measured. This is not usually reported in the test results. What other factors affect the PSA and Free PSA measured values?

2. What factors does the 4K Score measure that are different from the PSA test? Are the two measurements independent or do they overlap?

3. Are there any other conditions that would result in an elevated PSA or 4K Score besides the presence of prostate cancer?

4. Should the 4K Score carry more weight when making a biopsy decision?

5. If after a biopsy, no prostate cancer is found, does that mean it will eventually develop if the PSA and 4K Scores continue to rise?

[professoreden]

Hi. I think that many of the answers to your questions are covered in http://www.theprostateclinic.org/community/viewtopic.php?f=5&t=803.

Total PSA is elevated by age, prostate size, prostate injury (such as biopsy), urinary infection, bladder outlet obstruction and ejaculation, as well as cancer, whereas free PSA is not affected by these factors. A good % free PSA (free PSA/total PSA x 100) is over 25%. Free PSA levels of less than 15% are associated with a higher risk of prostate cancer.

The 4K score http://clinical.opko.com/how-does-4kscore-test-work and free PSA tests are two quite separate markers. Neither is wholly specific (only affected by the presence or absence of cancer) or wholly sensitive (picks up all cases) for detecting prostate cancer and represent different ways of looking at the same problem. When used together they can increase the accuracy of identifying the best men (i.e. those most at risk of prostate cancer) to biopsy.

If a biopsy is negative (i.e. shows no cancer) then the risk of cancer in that man is not zero as small cancers can sometimes be missed, especially if the biopsies were done blind (i.e. not MRI-targeted) and too few biopsies were done for the size of the prostate (increasing the sampling error). Follow up with tests such as PSA is important in these men but an elevated test results does not mean that cancer will eventually be found in all of these men.