What kind of prostate cancers do we miss on multiparametric magnetic resonance imaging?

Abstract

To analyse the characteristics of prostate cancers (PrCa) detected following negative multiparametric magnetic resonance imaging (mpMRI). Eight hundred and thirty patients with elevated prostate-specific antigen (mean 11.9 μg/l) underwent mpMRI of the prostate at 1.5 Tesla with endorectal coil. The characteristics of all PrCa detected within 2 years after a negative mpMRI were analysed. Primary Gleason grade 4 or any grade 5 PrCa were considered high-grade (HG), Gleason score 3 + 4 intermediate grade (IG) and Gleason score ≤3 + 3 low-grade (LG). Tumour size was considered 'small' when <1 cm on radical prostatectomy specimen or limited to ≤2 cores on prostate biopsy. mpMRI was negative in 391 patients (47.1 %). In 124 patients (31.7 %) PrCa was detected within 2 years. Eighty-four (67.7 %) were LG, 22 (17.7 %) IG and 18 (14.5 %) HG. 119 (96.0 %) of the missed PrCa were organ-confined. The negative predictive value was 95.4 % (373/391) for HG PrCa. Among the 18 missed HG PrCa, 15 (83.3 %) were organ-confined and 12 (66.6 %) were small. The majority of missed tumours on mpMRI were low grade and organ-confined. In patients with elevated PSA and a negative mpMRI, consideration could be given to continued surveillance rather than immediate biopsy. • The majority of missed prostate cancers were low grade and organ-confined. • In patients with a negative mpMRI a biopsy may be postponed. • mpMRI had a negative predictive value of 95.4 % for high-grade prostate cancer.