Targeted biopsy of the prostate: improvement in detection of high-grade cancer, or the Will Rogers phenomenon?

2019 
OBJECTIVE: The advent of targeted prostate biopsies to suspicious lesions based on imaging confers improved detection of clinically significant prostate cancer. The oversampling of these lesions is likely to better represent the cancer grade. However, such grade inflation might lead to the Will Rogers phenomenon. This study aims to investigate whether patients with Gleason 3+4 cancer on transrectal biopsy are upgraded following transperineal MRI-targeted biopsy & whether this has implications for current clinical practice. PATIENTS AND METHODS: This retrospective analysis examined 107 consecutive patients presenting at a single tertiary referral centre (July/2012-July/2016) with prostate cancer of Gleason score 3+4 on transrectal ultrasound-guided systematic non-targeted TRUS-biopsy who then underwent a multi-parametric MRI followed by MRI-targeted transperineal prostate biopsy for accurate risk stratification and localization. RESULTS: Mean (SD) age was 67.0 (8.0), median (IQR) PSA 6.2 (4.7-9.6) ng/ml. Eighty-four of 107 (78.5%) had Gleason 3+4 on both transrectal systematic biopsy and transperineal MRI-targeted biopsy. Nineteen (17.8%) were upgraded to Gleason 4+3, 3 (3.0%) to Gleason 4+4 and a single (1.0%) patient to Gleason 4+5. These differences were significant (p=0.0006). Likewise, 23/107 (22%) of patients had higher risk disease based on their targeted biopsies. CONCLUSION: The use of targeted biopsy in men with impalpable cancer, ultimately upgrades 1 in 5 men from favourable intermediate to unfavourable intermediate risk disease or worse. This has significant clinical implications for men considering active surveillance or radical treatment. Our risk calculators must now be validated using these data from targeted biopsy as the technique becomes widely adopted.
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