Why Does the PSA Velocity Matter?

The PSA (prostate specific antigen) test has been used extensively around the world to detect and monitor for prostate cancer.

For many years, physicians have been using the absolute value of PSA to determine a man's risk for prostate cancer or whether his cancer has returned or progressed. In recent years, however, it has become more obvious that the rate of change of the PSA level (or PSA velocity) may be just as important as the raw number itself.

The New Role for PSA Velocity

Many prostate cancer experts now consider not only the PSA level, but how fast it is changing when determining whether to order further tests, when to start treatment, or what to tell their patients about prognosis.

Numerous studies have now shown that a high PSA velocity (for example rapid doubling time of PSA or a rise of 0.35 ng/mL or more per year) may signal a rapidly growing cancer regardless of how high the absolute PSA level is.

Here's an example of what I mean:

A man goes for his routine screening PSA test and it comes back at 2.0 ng/mL. He is otherwise healthy and his physician is unconcerned by the result since 2.0 is not a "high" level in most cases. But, last year his PSA level was 1.0 ng/mL and the year before it was 0.5 ng/mL.
Should these results worry him or his doctor?

Based on mounting evidence, the answer is likely "yes." In this example, a relatively low PSA level of 2.0 could be waved off as "normal." However, this man's PSA has doubled each year for two years. This is a high rate of change of PSA (such as a high PSA velocity) and could likely signify a rapidly growing cancer.

It is important to keep track of your own PSA levels over the years and alert your doctor to any trends that you notice. Physicians see thousands of patients a year and may simply overlook the fact that your PSA has been increasing rapidly.

_Sources: 

Carter HB, Ferrucci L, Kettermann A, et al. Detection of life-threatening prostate cancer with prostate-specific antigen velocity during a window of curability. Journal of the National Cancer Institute 2006; 98(21):1521–1527.
Ng MK, Van As N, Thomas K, et al. Prostate-specific antigen (PSA) kinetics in untreated, localized prostate cancer: PSA velocity vs PSA doubling time. BJU Int. 2008 Oct 16.