PSA velocity has the potential to be highly valuable in detecting prostate cancer, and in distinguishing it from BPH early—particularly now, when an increasing number of men are returning to their doctor every year for a digital rectal examination and PSA test. PSA velocity is a fluid continuum, not a cut-and-dried, one-shot reading. It’s like having a prostate barometer—your doctor doesn’t have to wait for the PSA score to reach a magic number (currently, it’s 4 nanograms per milliliter). With PSA velocity, what matters is a significant change over time—an average consistent increase of more than 0.75 nanograms per milliliter a year, over the course of three tests separated by at least 12 to 18 months. Say over 24 months a man’s PSA level went up from 1.2 to 2.3 to 3.6. Clearly, something’s going on here. This obvious, steady rise could enable a doctor monitoring PSA velocity to detect clinically significant, curable prostate cancer in its earliest, most subtie stages, instead of waiting for the PSA level to reach the magic 4, and then doing further tests. “So the potential for PSA velocity means we can make a more accurate diagnosis of prostate cancer at even lower levels then the raw cutoff of 4, because it works at any level,” says one of the researchers. (At present, it’s unclear what rate of change is significant in men with PSA greater than 10.) Also, PSA velocity is more specific. If doctors use the PSA level of 4 as a cutoff point, about 40 percent of men who only have BPH undergo unnecessary biopsies. But with PSA velocity, this number is reduced; only 10 percent of men with BPH undergo an unnecessary biopsy.
Because of such studies, many doctors are excited about PSA velocity. However—although it’s a big improvement over looking at a bald PSA score and trying to figure out what it means—even PSA velocity isn’t a perfect system. One big point to remember: 25 percent of men with prostate cancers that are growing do not have a big increase in their PSA. So, just because your PSA isn’t high, and just because your PSA isn’t going up, that doesn’t mean you don’t have cancer, and it doesn’t mean that your cancer isn’t growing.
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