December 13, 2011

Biopsy referral after PSA screening stays consistent

Study finds no movement toward more aggressive follow-up

Seattle, WA—After the U.S. Prostate Cancer Prevention Trial found cancer in many men with low levels of prostate specific antigen (PSA), many debated  which PSA level should lead to a biopsy recommendation. But the U.S. Preventive Services Task Force recently concluded, amid considerable controversy, that the evidence  does not support recommending PSA screening for men under 75 years old at all, because the risks outweigh the benefits.

Now, a study shows that physicians at Group Health Cooperative were being conservative in biopsy  referral even before the Task Force recommendation. The study in the January  2012 American Journal of Preventive Medicine was e-published on December  13, 2011.

“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 at Group Health,” said lead author Steven Zeliadt, PhD. Dr. Zeliadt is with the Department of Health Services at the Veterans Affairs Medical Center  in Seattle and  is also an affiliate investigator at Group Health Research Institute.

“In fact, we observed an opposite pattern, with biopsies becoming slightly less common over the study period,” he said. “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.”

Controversy is longstanding about what PSA threshold should  be used to refer men for biopsy. The generally accepted standard is 4.0 ng/mL. But some have urged lowering the level to 2.5 ng/mL, abandoning a specific cutoff altogether, or measuring the PSA velocity—or change over time—instead of absolute level. Dr. Zeliadt and his colleagues set out to determine if the actual biopsy referral practices in a community setting had changed in response  to new recommendations, and to determine if PSA velocity is associated with follow-up biopsy.

The study examined PSA tests in Group Health patients between 1997 and 2008. The final sample included 111,369 index tests among 54,831 men. For each test, the study evaluated the PSA level and velocity and the specific follow-up: receiving a biopsy within a year after the test date; attending a urology appointment within a year without biopsy; additional PSA testing within a year with no urology visit; and no PSA-related follow-up.

The researchers found that of tests with a PSA value greater than 4.0 ng/mL, 28 percent led to a biopsy within 12 months, and 39 percent were followed up by a urologist but did not result in a biopsy. Biopsies were slightly more common in the early years of the study, but biopsy rates did not differ over time for men with mild to moderate PSA levels. The threshold used for biopsy referral appeared not to change over time.

PSA velocity was strongly associated with biopsy. Among men whose PSA tests exceeded 4.0 ng/mL, those with a rapidly rising velocity were more likely to undergo biopsy. This rate was also consistent across the years of the study.

“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,” Dr. Zeliadt said.

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

The National Cancer Institute funded this research.  

Dr. Zeliadt’s co-authors were Diana  S.M. Buist, PhD, MPH; Robert J. Reid, MD, PhD; David C. Grossman, MD, MPH, of Group Health Research Institute; Jian Ma, MD, PhD,  of Group Health; and Ruth Etzioni, PhD,  of the Fred Hutchinson Cancer Research Center.

American Journal of Preventive Medicine   

The American Journal of Preventive Medicine is the official journal of The American College of Preventive Medicine and the Association for Prevention Teaching and Research.  It publishes articles on prevention research, teaching, practice, and policy.  Original research is published on interventions aimed at preventing chronic and  acute disease and promoting individual and community health. The journal  features papers that address the primary and secondary prevention of important  clinical, behavioral, and public health issues such as injury and violence, infectious disease, women's health, smoking, sedentary behaviors and physical  activity, nutrition, diabetes, obesity, and alcohol and drug abuse. Papers also address educational initiatives aimed at improving the ability of health  professionals to provide effective clinical prevention and public health services. The journal also publishes official policy statements from the two co-sponsoring organizations, health services research pertinent to prevention and public health, review articles, media reviews, and editorials.

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