1 in 9 men will be diagnosed with prostate cancer at some point in his life. And those men who survived did so because they got checked for prostate cancer, it was found and treated, and they have gone back to living their life.
When should men start getting screened for prostate cancer? “All men should get a baseline PSA in their forties,” says New York University urologist Stacy Loeb, M.D. PSA stands for “prostate-specific antigen.” While PSA is prostate-specific, it is not cancer-specific, which means, basically, that it’s a helpful but imperfect test.
“This is especially true for men at higher risk due to family history or African-American descent, but the baseline PSA also identifies others at higher risk who may need more close attention.” In addition to getting the baseline PSA blood test, you need a very brief prostate exam (the doctor feels your prostate through the rectum).
Loeb’s research with urologist William Catalona, M.D. of Northwestern University, and others has helped establish what a good baseline number should be. “We looked at the PSA levels of 36,000 men, and found that for men in their forties, the average PSA level was 0.7. For men in their fifties, it was 0.9.”
What does this mean for you? “If you have a PSA level that’s higher than that when you’re in your forties, you are at a greater risk of developing prostate cancer, and actually of developing life-threatening prostate cancer. If your PSA is more than 1.0 and you’re in your forties, you are at higher risk.”
That doesn’t mean that you have cancer, and it doesn’t mean that you need a biopsy immediately, Loeb emphasizes. “It’s a useful number to give one more piece of information to your doctor. It just means that you are at higher risk, and you need to be monitored more closely than somebody who does not have any prostate cancer risk factors.”
While PSA is prostate-specific, it is not cancer-specific, which means that it’s a helpful but imperfect test.
If your baseline PSA is within the guidelines for your age and you don’t have any other risk factors (like a family history or being of African ancestry), you just need to get follow-up PSA tests every other year or so.
If your PSA is a little higher, or if it begins to rise, your doctor might suggest further tests—other blood tests or imaging—or a biopsy. But every man’s situation is different. “Historically, we just used the absolute level of PSA to decide about biopsy,” says Loeb. “Just one threshold was used for every man, irrespective of his risk factors. The cutoff was 4, and above 4 was defined as abnormal.”
But over the last two decades, scientists discovered that this cutoff was not nearly accurate enough. Many men with a PSA lower than 4 have cancer that needed to be treated, and many men with a PSA higher than 4 don’t have cancer. As men age, their prostate tends to get bigger, and this causes the PSA number to get higher (see below). Prostatitis, acute or chronic inflammation of the prostate, can also alter the PSA number.
A Risk-Adapted Approach
“We now look at PSA as more of a continuous variable,” says Loeb. “There is no one cutoff number that excludes the risk of prostate cancer. The number reflects your risk along the spectrum. If it’s 2, your risk is higher than if it’s 1. If it’s 3, that’s a higher risk than 2, and as the PSA increases, the risk of prostate cancer and aggressive disease increases. We have now moved toward a more risk-adapted approach, using multiple factors together to give men a more personalized estimate of their risk, and to help determine if they need a biopsy.”
Other tests are available to help determine if the PSA is more likely coming from cancer or BPH, and if the cancer is likely to be high-risk. These “second-line” tests can provide complimentary information, adding another piece to the puzzle. Some of these include:
Free PSA: “PSA is found in two main forms in the blood. It’s either bound with proteins, which is called ‘complexed PSA,’ or it’s ‘free PSA,’ which is not attached to proteins. If there is more free PSA, that is a good sign, because it suggests that you have benign enlargement.” 4K Score test and Prostate Health Index (PHI): If you have a slightly elevated PSA, these tests can help predict whether you are likely to have prostate cancer, especially high-risk prostate cancer. “Both of these are PSA-based blood tests,” explains Loeb. “They use different subforms of PSA combined together to better stratify the risk, and both of them are more specific for clinically significant prostate cancer,” cancer that needs to be treated.
The National Comprehensive Cancer Network (NCCN) guidelines say that if PSA is more than 3, “the threshold used in European trials,” Loeb notes, “then you can proceed with a biopsy. But these second-line tests can help you and your doctor make a better, more informed decision.”
Another important thing to know is your PSA density: This is your PSA score, divided by the volume of your prostate (how big it is), as determined by transrectal ultrasound or MRI, a noninvasive imaging test. Just as BPH can cause the prostate to make more PSA, so can a small cancer. “If your PSA is in a borderline elevation, is it because your prostate is big, or because there’s a little tumor there pumping out more PSA? If the prostate is very small and the PSA is high, that’s worrisome,” Loeb adds. “It could be that a cancer is causing a PSA level disproportionate to the size, so the PSA density really helps us understand the meaning of the PSA value.”
New PSA-based tests and biomarkers continue to be developed, and “many doctors have not yet had experience with all of these markers,” says Loeb, who gives lectures on prostate cancer testing twice a month in different countries. “There has been a rapid expansion of new tests, so it’s helpful for men to know what the tests are, and whether they’re a candidate for them.”
