Multiparametric magnetic resonance imaging (mpMRI) helps improve detection of clinically significant prostate cancer (PCa), but by itself cannot replace confirmatory or surveillance prostate biopsies, investigators concluded.
In a single-center study, 21.5% of men on active surveillance (AS) for low-risk (Grade Group 1) PCa and a negative mpMRI scan were found to have Grade Group 2 or higher cancer on subsequent prostate biopsies.
“These findings suggest that there is a persistent subset of men on AS with grade reclassification undetected by mpMRI,” Carissa E. Chu, MD, and colleagues at the University of California, San Francisco, reported online in European Urology.
The study included 344 men on AS who had at least 1 mpMRI scan and biopsy after their PCa diagnosis. The men had 408 mpMRI scans during a median 71 months on AS. The median time between prostate biopsies was 16.5 months. The overall negative predictive value (NPV) of a negative mpMRI scan was 79.5%. The NPV ranged from 74.4% at the confirmatory (second) biopsy to 84.6% for all subsequent biopsies up to the fourth surveillance biopsy, according to the investigators.
Further, among men with a PSA density (PSAD) of 0.15 ng/mL/cm3 or higher, the overall NPV of mpMRI was 65.5% and ranged from 57.1% to 73.3% across serial mpMRI scans, according to the investigators.
“This is the first study reporting the NPV of mpMRI at multiple time points during AS,” the investigators wrote. “It supports previous findings that a percentage of clinically significant prostate cancers remain undetectable by mpMRI.”
The authors concluded that mpMRI alone is insufficient to rule out grade reclassification among men on AS, especially among those with a PSA density of 0.15 ng/mL/cm3 or higher, and, in particular, mpMRI should not replace confirmatory biopsy.
Chu CE, Lonergan PE, Washington SL, et al. Mutiparametric magnetic resonance imaging alone is insufficient to detect grade reclassification in active surveillance for prostate cancer [published online July 3, 2020]. Eur Urol. doi: 10.1016/j.eururo.2020.06.030