ORLANDO, FL USA (UroToday.com) - Men with low-risk prostate cancer are increasingly offered the option of active surveillance, involving serial prostate biopsy in order to assess for progression of disease. While the definition of “low-risk” remains controversial, all of the established criteria for active surveillance eligibility are based on template 12-core biopsy of the prostate. This approach is widely adopted, but may be problematic as nearly one-third of all men on active surveillance harbor more aggressive disease as found on final pathology than predicted by 12-core biopsy. Multiparametric MRI-ultrasound fusion-targeted biopsy has been demonstrated to detect higher grade cancer than 12-core biopsy in multiple studies, but has not been studied in the context of active surveillance. In order to evaluate the performance of targeted biopsy and MP-MRI in monitoring for disease progression, Dr. Annerleim Walton-Diaz and colleagues at the National Cancer Institute conducted a study of men with very low-risk disease who underwent serial imaging and biopsy, representing the largest series of its type to date.
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Patients who met the Epstein criteria for active surveillance underwent an initial MP-MRI with fusion biopsy and 12-core biopsy, and thereafter were followed with a yearly MP-MRI and biopsy session. The study endpoint was progression to a Gleason sum of 3+4 in any core of a targeted or 12-core biopsy. A change in MP-MRI findings, including an increase in lesion diameter, number of lesions, or lesion suspicion score was used as a metric to assess the predictive power of MRI for increase in tumor grade. Over a median follow-up of 18 months, 10 of the 53 patients in the cohort progressed to Gleason 3+4 disease. The majority of this pathologic progression was detected by targeted biopsy. While the positive predictive value of MRI for an increase in Gleason score was 50%, the negative predictive value was high at 84%. Sensitivity and specificity were comparable at 70% and 72% respectively.
These findings may demonstrate that patients with very low-risk prostate cancer can be safely followed with serial MP-MRI if imaging findings remain stable. Where biopsy is indicated, MRI-targeted biopsy detects a majority of progression. As such, MP-MRI and fusion biopsy may be useful as adjuncts or replacements for template 12-core biopsy, specifically in the follow-up of men on active surveillance. Further studies are necessary to delineate the indications, eligibility criteria, and interval of follow-up for introducing these modalities into clinical practice.
Click HERE to listen to the presentation by Annerleim Walton-Diaz, MD
Click HERE to view the presenter's slides from this session
Presented by Annerleim Walton-Diaz at the American Urological Association (AUA) Annual Meeting - May 16 - 21, 2014 - Orlando, Florida USA
National Cancer Institute (NCI), Bethesda, MD USA
Written by Nabeel A. Shakir and Zhamshid Okhunov, University of California (Irvine), and medical writers for UroToday.com