Model Predicts Risk of Prostate Cancer After Negative Biopsy

Piecewise exponential model considers patterns of change in risk factors over time

THURSDAY, Feb. 25 (HealthDay News) -- A model that takes changes in risk factors over time into account can predict who is at high risk of developing prostate cancer among men whose biopsies are initially negative, according to a study published online Feb. 22 in the Journal of Clinical Oncology.

Using data from 1,871 men with initially negative biopsies and at least one follow-up biopsy, Peter H. Gann, M.D., from the University of Illinois at Chicago, and colleagues developed a piecewise exponential model to estimate the probability of prostate cancer detection over time for subsets of patients with specific patterns of change in their risk factors.

After a mean follow-up of 2.8 years, the researchers found that prostate cancer developed in 465 patients. Although several factors were independently associated with cancer detection, the strongest predictors were serum prostate-specific antigen levels, high-grade prostatic intraepithelial neoplasia or atypical glands, gland volume, and number of repeat biopsies. Assigning men into risk groups, men with high-risk event histories had a 20-fold higher incidence of prostate cancer over five years than men with low-risk histories.

"Piecewise exponential models provide an approach to longitudinal analysis of prostate cancer risk that allows clinicians to see the interplay of risk factors as they unfold over time for individual patients," Gann and colleagues conclude. "The results show that many men with common event histories have a low cumulative risk of prostate cancer detection up to five years after a negative biopsy, and thus, clinicians can help these patients by avoiding the cost and psychological distress of unnecessary biopsies."

Several authors reported advisory, consulting, or financial relationships with pharmaceutical and biotechnology companies.

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