Prostate cancer is usually diagnosed two ways, either with a PSA elevation, which is a blood test that’s elevated, or on a digital rectal examination, an examination of the prostate.
PSA is a protein; it’s produced by the prostate and it seeps into the bloodstream. It’s a simple blood test that’s taken. If that level is elevated, in general, your chance of prostate cancer is high.1
We have various ways of using the PSA. We use the absolute PSA level, and traditionally we used to use a level of four as the cut-off.2 More recently, we’ve used age-related levels, because your PSA goes up as you get older.2 There’s been data to show that we should use a new cut-off of 2.5, seen particularly in young men.3, 4 If their PSA is above 2.5, the risk of cancer is significantly elevated.3
Another very important way of using PSA is the velocity of the rate of rise of PSA. PSA velocity measures how fast PSA levels in the blood increase over time. A high PSA velocity may be a sign of prostate cancer and may help find fast-growing prostate cancers.2 If the PSA, even if it’s low, is rising reasonably quickly, the risk of cancer is elevated.
The last thing we use PSA for is the free-to-total ratio. PSA is a protein; it floats around the bloodstream, some of it’s free-floating, some is bound to a protein. If we measure the amount that’s free-floating versus the total amount, we get a ratio test. If you have a low ratio, your chance of prostate cancer is higher than if you have a high ratio.5
We also diagnose prostate cancer on a digital rectal examination (DRE), and that’s a very simple test. Some people are quite concerned about it, but it’s very painless. We examine the prostate and feel it. Generally, the prostate’s usually the size of a walnut; it’s smooth, there’s no nodules, no lumps or bumps, and it feels like the tip of your nose. If it feels firmer than that, then that can be a sign of possible prostate cancer. The DRE can be a quick and helpful way to check if your prostate is showing any physical signs of cancer.6
It’s important to do both PSA testing and DRE, because 10% of cancers don’t actually produce PSA.7 So, it’s important to do both tests.