A new study led by researchers at UC San Francisco and Kaiser Permanente has identified genetic predictors of normal prostate-specific antigen (PSA) levels in healthy men, which could be used to improve the accuracy of PSA-based prostate cancer screening tests.
Until recently, PSA tests for prostate cancer were considered an exemplar of successful early cancer detection leading to improved treatment outcomes. But over the past five years, a series of studies has suggested that the tests are not sensitive enough: frequent false positives lead to too many unnecessary medical procedures, and false negatives give men a false sense of security. In 2012, the test was given a “D” rating by the U.S. Preventive Task Force, and the test is no longer covered by some insurers.
“In the few years that PSA testing has become less popular, the use of the test has declined and the number of prostate cancer diagnoses has dropped,” said John Witte, PhD, a UCSF professor of epidemiology and biostatistics and of urology, and co-senior author of the new study. “Disturbingly, some of the cases that are detected are now being diagnosed at a later stage, making successful treatment less likely. It’s a big conundrum for the field.”
One of the problems with current PSA tests is that they are a one-size-fits-all measurement of a protein that men naturally produce at different levels. The new genome-wide association study — led by Witte and co-senior author Stephen K. Van Den Eeden, PhD, a research scientist at Kaiser Permanente Division of Research and professor of urology at UCSF — suggests that the PSA test could regain its place in cancer prevention by factoring in genetic variations that affect the amount of PSA different men naturally produce.