Session: MP44: Prostate Cancer: Detection & Screening II
MP44-02: Systematic and MRI-targeted biopsy strategies for the detection of radiorecurrent prostate cancer: an analysis from the FOcal RECurrent Assessment and Salvage Treatment (FORECAST) trial
Introduction: Planning salvage focal therapy for radiorecurrent prostate cancer requires localization of any intra-prostatic disease. Whilst saturation biopsies maximize cancer detection, they increase operative time and morbidity. Using the paired validation FORECAST trial, we tested 5 alternative biopsy strategies. Here, men with radiorecurrence underwent multiparametric MRI followed by transperineal template mapping (TPM) and MRI-targeted biopsies (MRI-TB). Methods: FORECAST (NCT01883128) enrolled 181 men from 6 UK centers. The prostate was divided into quadrants (right/left; posterior/anterior). Strategies evaluated were: 1) MRI-TB only; 2) MRI-TB and systematic biopsy of the other ipsilateral quadrant; 3) MRI-TB and systematic biopsy of the contralateral posterior quadrant; 4) MRI-TB and systematic biopsy of the other ipsilateral and contralateral posterior quadrants; 5) MRI-TB and contralateral hemi-gland systematic biopsy. The number of missed cancers per strategy was compared against whole-gland MRI-TB and TPM biopsy. Results: 84 men underwent MRI-TB and TPM biopsy, and 73 (87%) had recurrent cancer. Strategy 1 missed 6 cancers (8%). Strategies 4 and 5 missed 2 (3%) and 3 (4%) cancers, respectively, not significantly different to strategy 1 (p=0.3 and 0.5, respectively). Strategies 2 and 3 missed 2 (3%) and 5 (7%) cancers. For cancer defined as Grade Group (GG) =2 and/or maximum cancer core length (MCCL) =4mm (n=73), strategy 1 missed 9 cancers (12%), and strategies 4 and 5 missed 2 (3%) and 4 (5%) cancers, respectively (p=0.06 and 0.7, respectively). Strategies 2 and 3 missed 3 (4%) and 7 (10%) cancers, respectively. For cancer defined as GG =3 and/or MCCL =6mm (n=67), strategy 1 missed significantly more cancers (8, 12%) than strategy 4 (1, 1%; p=0.03) but not strategy 5 (4, 6%; p=0.4). Strategies 2 and 3 missed 3 (4%) and 6 (9%) cancers, respectively. Conclusions: Strategies 2-5, which systematically sampled additional quadrants outside of the MRI target did not significantly increase cancer detection of any definition compared to MRI-TB alone, which missed <10% of recurrent cancer. However, for cancer defined as GG =3 and/or MCCL =6mm, MRI-TB alone missed significantly more cancer than strategy 3. Depending on cancer definition, it may therefore be possible to omit whole gland biopsy for shorter biopsy protocols whilst maintaining high diagnostic yield. SOURCE OF Funding: Funded by the Pelican Cancer Foundation, the US National Institutes of Health, and the UK Medical Research Council.
