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prediction of ECE, SVI, and nodal disease included age, PSA,

clinical stage, primary Gleason score 4 or 5, and percentage

of involved cores/total cores. All of these, except for age and

PSA, were significant predictors of outcome, with primary

Gleason 4 or 5 being the strongest factor associated with

each outcome (odds ratio [OR] 2.3,

p

<

0.01 for ECE; OR 5.7,

p

<

0.0001 for SVI; OR 7.147,

p

<

0.01 for N+ disease). When

MRI results were added to each model, they showed a

significant association with the outcomes (all

p

<

0.001).

Combined MRI and each model outperformed individual

models alone at all levels in the receiver-operating

characteristic analysis (Supplementary Table 2). Comparing

Partin and Partin + MRI predictive models, the AUC was

0.61 versus 0.73 for ECE, 0.75 versus 0.82 for SVI

( Fig. 1

), and

0.82 versus 0.85 for N+ (Supplementary Fig. 1). Comparing

CAPRA and CAPRA + MRI models, the AUC was 0.69 versus

0.77 for ECE, 0.75 versus 0.83 for SVI

( Fig. 1 )

, 0.82 versus

0.85 for N+ (Supplementary Fig. 1).

Our results suggest that MRI information can provide an

added value when compared with clinical-based, Partin

Table, or CAPRA score models alone for the prediction of

adverse histopathological outcomes at RP. Based on our

data and on the nature of our cohort, patients with doubtful

clinical findings and intermediate to high risk disease could

benefit the most from preoperative MRI. Few studies have

explored the potential additional value of MRI, and those

that have are relatively underpowered. Feng et al

[6]

compared the predictive accuracy of MRI and clinical

models (Partin Tables and Memorial Sloan Kettering Cancer

Center nomogram) for ECE finding a minor improvement in

diagnostic accuracy after addition of MRI to the model (AUC

for Partin Tables and Memorial Sloan Kettering Cancer

Center of 0.85 and 0.86, respectively, increased to 0.93 and

0.94 after addition of MRI). The magnitude of the difference

they detected is likely lower than ours because they had a

lower risk cohort and thus had lower rates of ECE, which

would falsely inflate the AUC for models that predicted

against ECE and underestimate the utility of an MRI. For

instance, 95% of their cohort was either cT1c or cT2a, while

only 66% of our core met these criteria.

Gupta et al

[7]

compared the accuracy of 3-Tesla MRI and

Partin Tables in predicting ECE. This study did not analyze

the additional value of MRI to the Partin Tables, but rather

compared those two tools in alternative models, finding a

Partin accuracy similar to ours (AUC: 0.62) and a MRI AUC of

0.82. Again, however, the study population was small

(60 patients) and with a clear preponderance of clinically

low and intermediate-risk patients. Tay et al

[8]

used 3-Tesla

[(Fig._1)TD$FIG]

Fig. 1 – receiver operating characteristic (ROC) curves for extracapsular extension (ECE) and seminal vesicle invasion (SVI) prediction.

CAPRA = Cancer of the Prostate Risk Assessment; MRI = magnetic resonance imaging.

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