A recent study by researchers at Johns Hopkins University contains a fresh idea on how PSA screening tests might be made more informative. A small study, this research is unlikely to alter most recommendations on screening for prostate cancer using the PSA test. However, its findings about the value of measuring PSA “velocity” over time—instead of a PSA level at any one point in time—could sharpen clinical decision making.

Results of the study of 980 men were published in the November 1, 2006 issue of the Journal of the National Cancer Institute. The study found that paying attention to how much the level of prostate-specific antigen (PSA) increases in a man’s blood each year is worthwhile. Measuring the rate of change, the researchers suggest, could be more helpful than the current approach of looking for a PSA level higher than the “normal range.” Monitoring the changes in velocity from year to year could help identify men who will develop life-threatening cancer while their disease is still curable, said the lead author, in an article in the JHU Gazette (the newspaper of The Johns Hopkins University). Deaths 20 to 30 years later could have been predicted using this information, even before a high PSA level would have prompted the healthcare provider to order a biopsy.

The more predictive approach recommended by this study could make diagnosing more accurate. Using it might reduce over-diagnosis. Measuring PSA velocity could also help focus healthcare providers’ attention on cases at greater risk of developing into life-threatening disease. The Washington Post reports that “growing numbers of doctors are using the method already to help decide when to order a biopsy.”

The researchers also recommend that men have their first PSA test at around age 40, not at age 50 (a more common recommendation). Getting tested at this younger age, explains the lead author, establishes a baseline for future measurements. Given that recommendations already vary considerably—not only on the timing of PSA tests, but on their value—this recommendation is bound to spur further controversy and discussion.

In the same journal, an editorial by Timothy Church of the University of Minnesota School of Public Health, was encouraging. Church called these findings “another step on the road to more sophisticated use of quantitative methods.” This more mathematical approach to using the PSA test could “improve the understanding and accuracy of screening and prognosis in prostate cancer,” said Church. Instead of having just a “modest screening test,” laboratories might, as Church suggests, predict “not only the presence of cancer but also its lethal potential.”

Sources
S1
Carter, H. B., Ferrucci L., Kettermann A. et al. 1 Nov 2006. Detection of life-threatening prostate cancer with prostate-specific antigen velocity during a window of curability. J Natl Cancer Inst. 98(21):1521-7. On the Internet: http://jncicancerspectrum.oxfordjournals.org. Abstract accessed 19 Nov 2006.

S2
Ventura J. 6 Nov 2006. Newer approach urged in screening for aggressive prostate cancer. The JHU Gazette. 36(10). On the Internet: http://www.jhu.edu/?gazette/2006/06nov06/06screen.html. Accessed 19 Nov 2006.

S3
Neergaard L. Study eyes PSA tests for prostate cancer. Washington Post. 1 Nov 2006.

S4
Church, T. R. 1 Nov 2006. Prostate-specific antigen and prostate cancer prognosis (editorial). J Natl Cancer Inst. 98(21):1509-1510. On the Internet: http://jncicancerspectrum.oxfordjournals.org/cgi/content/full/jnci;98/21/1509. Accessed 19 Nov 2006.