Transperineal Magnetic Resonance Imaging-targeted Biopsy versus Transperineal Template Prostate Mapping Biopsy in the Detection of Localised Radio-recurrent Prostate Cancer

Abstract

AimsMulti-parametric magnetic resonance imaging (mpMRI) may identify radio-recurrent intra-prostatic cancer accurately. We aimed to compare visually directed MRI-targeted biopsies (MRI-TB) to an accurate reference standard – transperineal prostate mapping (TPM) biopsies with 5 mm sampling – in the detection of clinically significant cancer in men with biochemical failure after radiotherapy. Materials and methodsA retrospective registry analysis between 2006 and 2014 identified 77 men who had undergone mpMRI followed by MRI-TB and TPM. Clinical significance was set at two definitions of disease. Definition 1 was Gleason ≥ 4+3 and/or maximum cancer core length ≥ 6 mm. Definition 2 was Gleason ≥ 3+4 and/or maximum cancer core length ≥ 4 mm. ResultsOf the 77 patients included, the mean age was 70 years (range 61–82; standard deviation 5.03). The median prostate-specific antigen (PSA) at the time of external beam radiotherapy (EBRT) was 14 ng/ml (interquartile range 7.83–32.50). The most frequent EBRT dose given was 74 Gy over 37 fractions. Eight patients had iodine-seed implant brachytherapy or high dose rate brachytherapy. Neoadjuvant/adjuvant hormonal therapy use was reported in 38. The time from EBRT to biochemical recurrence was a median of 60 months (interquartile range 36.75–85.00). The median PSA at the time of mpMRI was 4.68 ng/ml (interquartile range 2.68–7.60). The median time between mpMRI and biopsy was 2.76 months (interquartile range 1.58–4.34). In total, 2392 TPM and 381 MRI-TB cores were taken with 18% and 50% cancer detection, respectively. Detection rates of definition 1 clinically significant cancer were 52/77 (68%) versus 55/77 (71%) for MRI-TB and TPM, respectively. MRI-TB was more efficient requiring 1 core versus 2.8 cores to detect definition 2 cancer. ConclusionMRI-TB seems to have encouraging detection rates for clinically significant cancer with fewer cores compared with TPM, although TPM had higher detection rates for smaller lower grade lesions.