FOIU 2018: Can MRI Replace Biopsy in Men on Active Surveillance? - NO

Tel-Aviv, Israel (UroToday.com) Reiter presented his view why serial MRI cannot replace biopsy in patients on active surveillance (AS) in prostate cancer (PC) patients. According to Reiter MRI is an excellent (although not perfect) for identification of “significant” tumors”. It has a high negative predictive value (NPV) that aids patient stratification for AS. Therefore, many Gleason grade group 1 (GGG1) tumors are not visible by MRI, and so there is nothing to follow. There is lack of evidence that serial MRI can add to or replace biopsy while on AS.

PIRADS scoring system predicts biochemical recurrence (BC) among patients with any biopsy Gleason grade 3+4 (Figure 1). Known predictors of detection of tumors on MRI include:
  • Larger size
  • Higher Gleason score
  • Index lesion status
  • Solitary tumor
Figure 1: PIRADS score predicts biochemical recurrence among patients with Gleason 3+4:
UroToday FOIU2018 PIRADS score predicts biochemical recurrence

In the detection of progression on AS by MRI, it was shown that it had a sensitivity of 50%, specificity of 87%, positive predictive values (PPV) of 50% and NPV of 87%. 1 Other studies demonstrated a sensitivity of 53% and a specificity of 80%. Unfortunately, 27% of Gleason score upgrades are detected only by TRUS biopsy.

In conclusion of this short overview, Reiter stated that MRI is a superb diagnostic tool and useful for patient stratification for AS. A majority of GGG1 index tumors are not visible by MRI and fewer than 20% of all multifocal tumors are visible, so in these lesions, there is nothing to follow. While there are anecdotal cases of progression, the data to date suggest that MRI is insufficient to detect most men with GGG1 progression. MRI has a sensitivity of 35-50% among all who are upstage/upgraded. It might have a greater role in AS of men with GGG2 but there is not enough data to date.

The bottom line is that with the currently available evidence-based medicine, MRI cannot replace the need for serial biopsy.

References:
1. Thurtle et al. BJU Int. 2018

Presented by: Robert Reiter, Geffen School of Medicine, UCLA, USA

Written by: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre @GoldbergHanan  at the 2018 FOIU 4th Friends of Israel Urological Symposium, July 3-5. 2018, Tel-Aviv, Israel

Read the Opposing Argument: Can MRI Replace Biopsy in Men on Active Surveillance?  - YES
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