Hans Heinzer, Till Krech, Sarah Minner, Agron Lumiani, Thorsten Schlomm, Ronald Simon, Stefan Steurer, Meike Adam, Sebastian Dwertmann Rico, Hartwig Huland, Maria Christina Tsourlakis, Markus Graefen, Guido Sauter, Christina Koop
Objectives
To determine the utility of our transgluteal magnetic resonance imaging (MRI)-guided prostate biopsy approach.
Patients and Methods
A total of 960 biopsy series, taken within the period of 1 year, were evaluated, including 301 MRI-guided and 659 transrectal ultrasonography (TRUS)-guided biopsies.
Results
The positivity rate and proportion of high grade cancers were significantly higher in MRI-guided than in TRUS-guided biopsies. Of 301 MRI-guided biopsies, 65.4% contained cancer while 57.2% of 659 TRUS biopsies contained cancer (P = 0.016). Gleason grade 3 + 3 = 6 disease was observed in 16.8% of 197 MRI-guided and in 36.1% of 377 TRUS-guided biopsies (P < 0.001). There was also a markedly higher quantity of cancer tissue in MRI-guided biopsies. In all cancers, the mean cancer surface area was 64.8 ± 51.6 mm2 in MRI-guided biopsies as compared with 23.0 ± 31.4 mm2 in non-MRI-guided biopsies (P < 0.001). With respect to the tissue quantity, superiority of MRI-guided biopsy was highest in Gleason grade 3 + 3 = 6 cancers (20.9 ± 27.9 vs 5.1 ± 10.2 mm2; P < 0.001) and in Gleason grade 3 + 4 = 7 cancers (59.7 ± 38.0 vs 17.7 ± 18.4 mm2; P < 0.001). Comparison of biopsy Gleason grades with findings in prostatectomy specimens was possible in 80 patients with MRI-guided and in 170 patients with non-MRI-guided biopsies. This comparison showed a very high but almost identical concordance of TRUS- and MRI-guided biopsies with the prostatectomy specimen findings. With both approaches, undetected high-risk cancers were present in ~10% of patients with low-risk biopsy results. A significant difference was observed, however, in the proportion of patients who had clinically insignificant cancers and who underwent surgery. The proportion of patients with Gleason grade 3 + 3 = 6 carcinoma in their prostatectomy specimen was 11.2% in the post-TRUS biopsy cohort, but only 2.5% in the post-MRI biopsy cohort (P = 0.021).
Conclusion
MRI-guided transgluteal prostate biopsy has a high detection rate for high-risk carcinomas, while the risk of detecting clinically insignificant carcinomas appears to be reduced. This may by itself lead to a reduction of unnecessary prostatectomies. Overtreatment may be further avoided by better applicability of molecular testing to MRI-guided biopsies because of the excessive amount of tissue available for analysis, especially in patients with potential low-risk carcinomas.
