A study has found that physicians screening patients for prostate cancer in a large Washington state health plan were being conservative in biopsy referrals even before a recent recommendation by an independent health panel against prostate specific antigen (PSA).

There is increasing concern about over diagnosis and over treatment among prostate cancer experts focusing on which PSA level should lead to a biopsy recommendation.

The US Preventive Screening Task Force said recently that current evidence does not support PSA screenings for men under 75 years old because the risks outweigh the benefits.

Biopsies are the only way for physicians to definitively diagnose prostate cancer.

Many have argued about lowering the PSA threshold standard from 4.0 nanograms per milliliter to 2.5 ng/mL, or abandoning the standard altogether, and instead measuring PSA velocity (the rate of change in PSA levels), to guide physicians about referring men for biopsy.

"Despite considerable recent debate about lowering the threshold for referring men to biopsy, we detected no change toward more aggressive biopsy referral practices in data spanning more than a decade for one integrated delivery system," said lead researcher Steven Zeliadt, PhD, of the Department of Veterans Affairs Medical Center in Seattle in a statement released Tuesday. "In fact, we observed an opposite pattern, with biopsies becoming slightly less common over the study period. This may reflect growing awareness of the problems of overdiagnosis and overtreatment—and the fact that many men die with prostate cancer but not from it," she said.

Study Methodology

Researchers from the study looked at data from 54,381 men who were given 111,369 tests in total between 1997 and 2008, and examined the PSA level, PSA velocity, follow-up testing and care given.

Researchers found that 28 percent of men were referred to biopsy within a year and 38 percent had a follow-up visit with an urologist.

Additionally, the study concludes that the thresholds for biopsy referral remained consistent over the study period, with PSA velocity, mainly rapidly increasing values, to strongly link to biopsies.

"PSA velocity has been promoted for many years as having value for predicting death from prostate cancer, although several recent studies and evidence from screening trials have demonstrated that in practice, velocity adds little value. This is not surprising given that PSA is a continuous marker, and a rapid rise may be likely to trigger follow-up, thus reducing rates of death from prostate cancer," said Zeliadt said.

"Even small changes in the PSA threshold can substantially alter the potential harms and benefits of screening. However, providers have limited evidence to help them discuss this with patients," Zeliadt concludes. "This study highlights the importance of acknowledging that how aggressively patients are referred for biopsy is an important component of the PSA screening discussion."

SEER Cancer statistics from the National Cancer Institute show that the median age at diagnosis for cancer of the prostate was 67 years of age, and about a third of men were diagnosed between the ages of 55 and 64, and about 35 percent were diagnosed between the ages of 65 and 74, from 2004 to 2008.