Natural History of Pathologically Benign Cancer Suspicious Regions on Multiparametric Magnetic Resonance Imaging Following Targeted Biopsy.

Abstract

PURPOSE: We determined the natural history of pathologically benign cancer suspicious regions on multiparametric magnetic resonance imaging following targeted biopsy. MATERIALS AND METHODS: Between January 2012 and September 2014, 330 men underwent prostate multiparametric magnetic resonance imaging. A total of 533 cancer suspicious regions were identified and scored on a Likert scale of 1 to 5 based on suspicion for malignancy with 5 indicating the highest suspicion level. Following multiparametric magnetic resonance imaging all men underwent magnetic resonance imaging-ultrasound fusion targeted prostate biopsy using ProFuse software and the ei-Nav|Artemis system (innoMedicus, Cham, Switzerland), and a computer generated 12-core random biopsy. We analyzed a cohort of 34 men with a total of 51 cancer suspicious regions who had benign prostate biopsies and underwent repeat multiparametric magnetic resonance imaging and prostate specific antigen testing at 1 year. Changes in the greatest linear measurement, the suspicion score and serum prostate specific antigen were ascertained. RESULTS: During 1 year the suspicion score distribution and the mean greatest linear measurement of the cancer suspicious regions decreased significantly (p <0.0001) while mean prostate specific antigen did not significantly change (p = 0.632). Two (3.9%), 15 (29.4%) and 34 cancer suspicious regions (66.7%) showed an increase, no change and decrease in suspicion score, respectively. No (0%), 21 (42.0%) and 29 cancer suspicious regions (58.0%) showed an increase of 20% or greater, no change and a decrease of 20% or greater in greatest linear measurement, respectively. Of the 2 cancer suspicious regions exhibiting an increased suspicion score neither showed a prostate specific antigen increase of 0.5 ng/ml or greater. CONCLUSIONS: Our study provides compelling evidence that few benign cancer suspicious regions increase in suspicion score and/or the greatest linear measurement within 1 year independent of the baseline suspicion score. Therefore, routinely repeating multiparametric magnetic resonance imaging at 1 year in men with pathologically benign cancer suspicious regions should be discouraged since it is unlikely to influence management decisions.