This post was written by Adam Thomas, MD, PPG – Urology.
September is Prostate Cancer Awareness Month, and I have the privilege of sharing important information every week on the topic. In a previous post, we discussed how common prostate cancer is for men over 50. Here, we will focus on how to screen for prostate cancer.
For more than 30 years, the best tools to screen for prostate cancer were a combination of a blood test and examination of the prostate. The blood test looks at prostate specific antigen (PSA), which is a normal enzyme that the prostate makes all the time. This enzyme has a known healthy function for men who are trying to reproduce. Larger prostates will naturally make more PSA. As men age, their prostates often enlarge for non-cancerous reasons, so their PSA is expected to slowly increase. For unknown reasons, men with prostate cancer tend to make even more of this enzyme. This is why checking PSA can be helpful. If a man’s PSA is higher than expected for the size of their prostate, they may be at an elevated risk for having prostate cancer.
PSAs that tend to go up and down like a ripple of water are typically indicative of non-cancerous causes. Even a sudden and very large jump in a PSA can be from infection or trauma, and is expected to eventually revert to baseline. Prostate cancer tends to steadily increase every year at a rate of about 0.75 - 1 point annually.
The second useful tool is the examination of the prostate, also called a digital rectal exam (DRE). Prostates tend to be soft and smooth. Prostate cancer often makes part of the prostate feel harder than expected. In addition, performing a DRE estimates the size of the prostate.
Ultimately, the combination of both PSA and DRE tests, and tracking results over time, delivers better insights than either of the tests alone or only performing the tests once.
New developments in screening
Over the past five years, new diagnostic tools have become available to identify men at risk for prostate cancer. One is a urine test, called an EXODX. There is also a blood test called a 4K that tests for four different types of PSA. Both of these tests can be used when it is unclear whether a man is at risk for prostate cancer.
None of these tools, PSA, DRE, EXODX or 4K, can diagnose prostate cancer. They are designed to identify who is at risk for prostate cancer. To diagnose prostate cancer, the patient needs a prostate biopsy.
I am also frequently asked about MRI of the prostate. This can be a very powerful diagnostic tool to screen for prostate cancer, particularly for men with a rising PSA who have had a prior benign prostate biopsy. I will focus more on both prostate biopsy and MRI of the prostate in future posts.
Screening is a critical piece of protecting yourself against prostate cancer. PSAs and DREs are very helpful and are best done over time to determine trends. Additional tests, such as EXODX and 4K, provide better clarity to determine if men are at risk for prostate cancer.