Combining diagnostic, surveillance prostate biopsy results useful

July 1, 2012

Combining the results of the diagnostic and first-surveillance prostate biopsies provides useful information about the risk of progression in patients being managed by active surveillance.

Key Points

Atlanta-Combining the results of the diagnostic and first-surveillance prostate biopsies provides useful information about the risk of progression in patients being managed by active surveillance, according to the findings of a recent retrospective study.

The research included data from 161 men who had at least two surveillance biopsies, of which the first was performed within 1 year of the diagnostic biopsy. During a median follow-up of 3.6 years, 46 men progressed, defined by presence of Gleason ⅘ cancer, more than two positive cores, or >20% involvement of any core.

Three multivariate models for predicting progression were constructed incorporating findings from the diagnostic biopsy, the first surveillance biopsy, or both, and their performance for predicting progression was assessed with Harrell's c-index. Data showed that the results of the combined model had significantly greater predictive accuracy than those using features of the diagnostic and surveillance biopsies individually (Harrell's c-index values 0.751 vs. 0.694 and 0.692, respectively), reported first author Viacheslav Iremashvili, MD, PhD, research fellow in the department of urology at the University of Miami Miller School of Medicine.

"Although all active surveillance patients have low-risk prostate cancer at diagnosis, up to 30% are found to have more extensive disease on surveillance biopsy. Our idea that combining diagnostic and surveillance biopsy findings might offer improved prognostic value was based on two assumptions: first, that the two biopsies, which are usually performed over a short time interval, can be looked at as one extended biopsy, and second, but more speculatively, that together they may reveal some dynamic component reflecting changes in tumor characteristics over time," Dr. Iremashvili explained.

"Based on our findings, we believe combining the information from the diagnostic and first surveillance biopsies can help us to better assess the prognosis of active surveillance patients and help these men make informed decisions about their management."

Dr. Iremashvili acknowledged the study has a number of limitations, as it is a retrospective analysis based on limited population size and follow-up. Furthermore, the predictive models included only biopsy criteria and no other potential predictive factors, such as PSA and its derivatives.

He also noted that the University of Miami criteria for active surveillance are more stringent than those of most other institutions, and for that reason, the findings of the study cannot necessarily be generalized to other active surveillance populations. At the University of Miami, active surveillance is offered only to men with no Gleason grade 4/5 disease, two or fewer positive cores, ≤20% tumor involvement in any core, cT1/T2a disease, and PSA <15.0 ng/mL.