PURPOSE: We aimed to determine the natural history of small index lesions identified on multiparametric-magnetic resonance imaging (MP-MRI) of the prostate by evaluating lesion-specific pathology and growth on serial MP-MRI.
MATERIALS AND METHODS: We performed a retrospective review of 153 patients who underwent a minimum of two MP-MRI sessions, on an institutional review board-approved protocol. Index lesion is defined as the lesion(s) with the highest cancer suspicion score based on initial MP-MRI of a patient, irrespective of size. Two study cohorts were identified: (1) patients with no index lesion or index lesion(s) ≤ 7 mm and (2) a subset with no index lesion or index lesion(s) ≤ 5 mm. Pathological analysis of the index lesions was performed following magnetic resonance/ultrasound fusion-guided biopsy. Growth rate of the lesions was calculated based on MP-MRI follow-up.
RESULTS: Patients with small index lesions measuring ≤ 7 mm (n=42) or a subset with lesions ≤ 5 mm (n=20) demonstrated either benign findings (86.2% and 87.5%, respectively) or low grade Gleason 6 prostate cancer (13.8% and 12.5%, respectively) on lesion-specific targeted biopsies. These lesions demonstrated no significant change in size (P = 0.93 and P = 0.36) over a mean imaging period of 2.31±1.56 years and 2.40±1.77 years for ≤ 7 mm and ≤ 5 mm index lesion thresholds, respectively. These findings held true on subset analyses of patients who had a minimum of two-year interval follow-up with MP-MRI.
CONCLUSION: Small index lesions of the prostate are pathologically benign lesions or occasionally low-grade cancers. Slow growth rate of these small index lesions on serial MP-MRI suggests a surveillance interval of at least two years without significant change.
Written by:
Rais-Bahrami S, Türkbey B, Rastinehad AR, Walton-Diaz A, Hoang AN, Siddiqui MM, Stamatakis L, Truong H, Nix JW, Vourganti S, Grant KB, Merino MJ, Wood BJ, Choyke PL, Pinto PA. Are you the author?
Urologic Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
Reference: Diagn Interv Radiol. 2014 Apr 30. Epub ahead of print.
doi: 10.5152/dir.2014.13319
PubMed Abstract
PMID: 24808435
UroToday.com Prostate Cancer Section
