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Single-centre experience with systematic transperineal stereotactic prostate biopsy plus magnetic resonance imaging targeted, transrectal ultrasound guided fusion biopsy

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Single-centre experience with systematic transperineal stereotactic prostate biopsy plus mpMRI targeted, TRUS guided fusion biopsy

1Hohenhorst JL, 1Musch M, 2Malik AB, 3Roggenbuck U, 1Taskiran B, 1Herholz R, 4Ebel T, 2Koch J-A, 1Kroepfl D

1 Kliniken Essen-Mitte, Department of Urology, Pediatric Urology and Urologic Oncology, Essen, Germany

2Kliniken Essen-Mitte, Department of Diagnostic and Interventional Radiology, Essen, Germany

3 University of Duisburg-Essen, Institute for Medical Informatics, Biometry and Epidemiology, Essen, Germany

 


Objectives

 

Prostate biopsy is still the only reliable diagnostic tool to prove the presence of prostate cancer (PCa). As such, prostate biopsy should provide a high cancer detection rate with a low associated morbidity. Furthermore, in the case of proven cancer, biopsy material should be representative allowing good assessment of tumour burden and location and exact Gleason grading [1]. To date prostate biopsy is usually performed transrectally under ultrasound guidance [2,3]. However, transrectal biopsy allows only a rough determination of tumour burden and location. In addition, following prostatectomy upgrading and downgrading of the final Gleason score is frequent. Especially in anterior cancers in enlarged prostates exact assessment of the tumour characteristics can be problematic as they are hardly accessible transrectally [4,5]. Furthermore, significant rates of hospital admissions are reported following transrectal biopsy due to septic complications, which can be fatal in few cases [6,7]. To overcome the obstacles mentioned above, attempts have been made to perform prostate mapping biopsy via a transperineal approach [8]. Hadaschik et al (2011) described a novel prostate biopsy system which integrates multiparametric magnetic resonance imaging (mpMRI) into intra-interventional transrectal ultrasound (TRUS) by software fusion allowing a very precise stereotactic navigation for both mpMRI targeted and systematic biopsies [4].

Here we present single-centre experience with introduction of systematic transperineal stereotactic prostate biopsy (STSBx) plus mpMRI targeted, TRUS guided fusion biopsy.


Methods

 

From May 2011, when STSBx plus mpMRI (3 tesla) targeted, TRUS guided fusion biopsy of the prostate was introduced in our clinic, through to June 2014, 300 patients underwent such a procedure. After exclusion of patients who underwent the procedure in the context of an active surveillance strategy or who had a previous negative STSBx plus mpMRI targeted, TRUS guided fusion biopsy, 289 patients formed the final study population. In 95 (33%) patients an initial biopsy and in 194 (67%) patients a repeat biopsy was performed. For assessment of suspicious mpMRI lesions the prostate imaging reporting and data system score (PI-RADS) was used: (using all four parameters: T2-weighted (T2), Diffusions-weighted (DWI), MR spectroscopic (MRSI) and dynamic contrast enhanced imaging (DCE)). In all cases not only targeted biopsies from suspicious lesions but also systematic biopsies were obtained to back up the whole prostate. To ensure best quality ultrasound imaging while targeted biopsies are obtained the systematic biopsies are always taken at the end. Each biopsy core is embedded in a single cassette with its apical end marked with blue ink. If cancer is found in a biopsy core a biopsy Gleason score (bGS) is assigned, and the percentage of cancer tissue in the core is determined. We used the patients’ records in our electronic patient documentation system to collect the intra- and post-interventional adverse events. All post-interventional complications were classified according to the Clavien-Dindo reporting system. Statistical analysis was conducted with the SAS® Software. Continuous variables are presented as medians with interquartile range [IQR] and range, and categorical variables as frequencies and percentages. We used the two-sided Mann-Whitney U test for analysis of continuous variables and the two-sided Fisher's exact test or the Chi-Square test for analysis of categorical variables with two or more characteristics, respectively. The Wald Chi-Square Test was used in the multivariate logistic regression model. The significance level was set at 0.05.


Results

 

Patient characteristics, pre-interventional tumour characteristics, mpMRIcharactersitics, and biopsy characteristics of the study population are summarized in Table 1. Patients who underwent repeat biopsy reported a median number of one (IQR 1-2, range 1-7) previous transrectal biopsies. Such patients showed a higher pre-interventional PSA and prostate volume than patients who underwent initial biopsy. PCa was detected in 144 (50%) patients – in 83/194 (43%) undergoing repeat and in 61/95 (64%) undergoing initial biopsy (Table 1). Only 16 of 144 (11.1%) patients with biopsy proven PCA showed an insignificant tumour that fulfilled the criteria for an active surveillance strategy (i.e. PSA ≤ 10 ng/ml and bGS ≤ 6 and cT1c-2a and tumour in ≤ 2 cores and ≤ 50 % tumour per core). Targeted and systematic biopsies would have detected PCa in 111/144 (77.1%) patients and in 118/144 (81.9%) patients, respectively. In 26 (18.1%) and 33 (22.9%) patients cancers were only found through targeted and systematic biopsies, respectively (Table 2). Those cancers detected only through targeted biopsy showed a significantly higher proportion of Gleason scores >= 7 than cancers detected only through systematic biopsy (57.1% vs. 29.4%; p = 0.039) (Table 2). Moreover, 16 out of 84 (19.0%) tumours with a bGS >= 7 were identified through targeted biopsies alone. By contrast, 10 (11.9%) Gleason score >= 7 tumours detected through systematic biopsies would have been missed if only targeted biopsies had been performed (Table 2). The zonal distribution of biopsy detected PCA is shown in Table 3. Among 144 patients with proven PCa the tumours were detected purely anteriorly in 29.2%, purely posteriorly in 19.4% and both anteriorly and posteriorly in 51.4% of cases. The rate of purely anteriorly located tumours was especially high in patients with repeat biopsy compared to patients with initial biopsy (37.3% vs. 18.0%; p = 0.031). In 35 (12%) patients 46 complications (42 grade 1-2 and 4 grade 3a/b) occurred, and no case of urosepsis was observed.


Conclusions

 

In both initial and repeat biopsy patients STSBx plus mpMRI targeted, TRUS guided fusion biopsy provided a high rate of PCa detection with a considerable proportion of purely anterior cancers. At the same time, however, detection of insignificant PC was low. Despite a clearly improved detection of significant PCa through targeted biopsies, additional systematic biopsies still seem to be essential, as a relevant number of significant PCas would have been missed using targeted biopsies alone. Morbidity associated with the procedure was low, and, most probably due to the transperineal approach, no septic complications occurred.



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