Biopsy techniques have made PSA test less predictive

Prostate specific antigen (PSA) levels typically have correlated with prostate biopsy results in the detection of prostate cancer, but that correlation no longer exists for men with a normal prostate exam, according to a new study published in the April 15, 2008 issue of CANCER, a peer-reviewed journal of the American Cancer Society. The study suggests that improved biopsy techniques make PSA less useful in prostate cancer screening.

PSA tests have been lauded as important diagnostic tools for prostate cancer, however much of the data used to make this conclusion were generated in the early to mid 1990s, when prostate biopsies were performed differently than they are today. Since that time, there has been an increase in the number of prostate biopsies performed and an increasing number of biopsy samples taken from each patient.

Douglas Scherr, MD, Michael Schwartz, MD, and colleagues at the New York Presbyterian Hospital of the Weill Medical College of Cornell University, in New York City, set out to assess whether changes in prostate biopsy practices might have changed the predictive value of PSA tests.

The researchers performed a retrospective analysis of all prostate biopsies performed at their institution between 1993 and 2005, finding 1,607 that satisfied their inclusion and exclusion criteria. Douglas Scherr, MD and his team divided patients into three groups based on when they received their biopsies: 1993-1997, 1998-2001, and 2002-2005. They examined each group for the number of biopsies performed, the number of positive biopsies, patient age, most recent PSA prior to biopsy, prostate volume, and number of biopsy samples taken. With these data in hand, they assessed potential correlations between PSA levels and positive biopsy rate.