To determine the added value of prostate MRI to the Prostate Cancer Prevention Trial risk calculator.

Between January 2012 and December 2015, 339 patients underwent prostate MRI prior to biopsy at our institution. MRI was considered positive if there was at least one Prostate Imaging Reporting and Data System 4 or 5 MRI suspicious region. Logistic regression was used to develop two models: biopsy outcome as a function of the 1) Prostate Cancer Prevention Trial risk calculator alone, and 2) combined with MRI findings.

When including all patients, the Prostate Cancer Prevention Trial with and without MRI models performed similarly (AUC 0.74 and 0.78, p=0.06). When restricting the cohort to patients with estimated risk of high grade (Gleason ≥7) prostate cancer <10%, the model with MRI outperformed the Prostate Cancer Prevention Trial alone model (AUC 0.69 and 0.60, p=0.01). Within this cohort of patients, there was no significant difference in discrimination between models for those with previous negative biopsy (AUC = 0.61 vs 0.63, p=0.76), while there was a significant improvement in discrimination with the MRI model for biopsy naïve patients (AUC = 0.72 vs. 0.60, p=0.01).

The use of prostate MRI in addition to the Prostate Cancer Prevention Trial risk calculator provides a significant improvement in clinical risk discrimination for patients with estimated risk of high grade (Gleason >7) prostate cancer <10%. Pre-biopsy prostate MRI should be strongly considered for these patients.