EURURO Vol. 72 No. 2

Introduction

A correlation with radical prostatectomy specimens has

demonstrated that multiparametric magnetic resonance

imaging (mpMRI) has excellent sensitivity in detecting

prostate cancer (PCa) with a Gleason score of 7

[1–3]

. As a

result, prostate mpMRI is increasingly used in patients with

a suspicion of PCa to localise abnormal areas before biopsy.

A large body of literature has shown that targeted biopsies

of suspicious lesions seen on mpMRI (TBx) improved the

detection of clinically significant PCa (csPCa), at least in the

repeat biopsy setting

[4–6]

. As a result, it is now

recommended that an mpMRI is performed before repeat

biopsy to allow TBx of suspicious lesions in addition to

standard biopsies

[7]

Some authors have recently suggested that, besides

improving csPCa detection, mpMRI could also be used as a

triage test so that patients with negative mpMRI findings

could obviate biopsy. Such a strategy remains highly

controversial

[8]

and depends upon the negative predictive

value (NPV) of mpMRI. Therefore, the European Association

of Urology Prostate Cancer Guidelines Panel undertook this

systematic review and meta-analysis to assess the NPV of

mpMRI in patients with a suspicion of PCa and, thus, its

potential role in eliminating unnecessary prostate biopsy.

Evidence acquisition

2.1.

Objective

Our primary aim was to systematically evaluate the

performance of negative prebiopsy prostate mpMRI in

predicting a negative biopsy result for overall PCa and csPCa

in biopsy-naı¨ve men and in men with previously negative

biopsies. A further objective was to explore and define

factors that may contribute to relevant thresholds in order

to provide guidance for future studies.

2.2.

Data acquisition and search strategy

The review was performed according to the Preferred

Reporting Items for Systematic Reviews and Meta-Analysis

(PRISMA) statement

[9] .

The review protocol was published

in PROSPERO database (

http://www.crd.york.ac.uk/ PROSPERO;

registration number CRD42015021929). Data-

bases searched included the Embase and OVID Medline

databases, the Cochrane database of systematic reviews,

and the Cochrane Central Register for Clinical Trials,

covering from January 1, 2000 to February 13, 2016. Sys-

tematic or standard prostate biopsies were used as

reference standards, with positive or negative cases of

PCa being determined by histopathological examination.

The detailed search strategy is presented in Supplement 1.

2.3.

Inclusion and exclusion criteria

Included studies focused on men who were assessed for

suspected PCa by mpMRI before undergoing prostate

biopsy. Studies enrolling both biopsy-naı¨ve men and men

who had undergone previous negative biopsies were

included. Prebiopsy prostate mpMRI was considered the

index test and comprised T2-weighted imaging (T2WI) and

at least one functional imaging technique (diffusion-

weighted imaging [DWI], dynamic contrast-enhanced

imaging [DCEI], or magnetic resonance spectroscopic

imaging [MRSI]). For inclusion, studies had to report on

and results reported at patient level for the detection of overall PCa or clinically significant

PCa (csPCa) defined as Gleason 7 cancer.

Evidence synthesis:

A total of 48 studies (9613 patients) were eligible for inclusion. At

patient level, the median prevalence was 50.4% (interquartile range [IQR], 36.4–57.7%) for

overall cancer and 32.9% (IQR, 28.1–37.2%) for csPCa. The median mpMRI NPV was 82.4%

(IQR, 69.0–92.4%) for overall cancer and 88.1% (IQR, 85.7–92.3) for csPCa. NPV significantly

decreased when cancer prevalence increased, for overall cancer (

= –0.64,

0.0001) and

csPCa (

= –0.75,

= 0.032). Eight studies fulfilled the inclusion criteria for meta-analysis.

Seven reported results for overall PCa. When the overall PCa prevalence increased from 30%

to 60%, the combined NPV estimates decreased from 88% (95% confidence interval [95% CI],

77–99%) to 67% (95% CI, 56–79%) for a cut-off score of 3/5. Only one study selected for meta-

analysis reported results for Gleason 7 cancers, with a positive biopsy rate of 29.3%. The

corresponding NPV for a cut-off score of 3/5 was 87.9%.

Conclusions:

The NPV of mpMRI varied greatly depending on study design, cancer preva-

lence, and definitions of positive mpMRI and csPCa. As cancer prevalence was highly

variable among series, risk stratification of patients should be the initial step before

considering prebiopsy mpMRI and defining those in whom biopsy may be omitted when

the mpMRI is negative.

Patient summary:

This systematic review examined if multiparametric magnetic reso-

nance imaging (MRI) scan can be used to reliably predict the absence of prostate cancer in

patients suspected of having prostate cancer, thereby avoiding a prostate biopsy. The

results suggest that whilst it is a promising tool, it is not accurate enough to replace

prostate biopsy in such patients, mainly because its accuracy is variable and influenced by

the prostate cancer risk. However, its performance can be enhanced if there were more

accurate ways of determining the risk of having prostate cancer. When such tools are

available, it should be possible to use an MRI scan to avoid biopsy in patients at a low risk of

prostate cancer.

Prostate biopsy

Risk stratification

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