Abstract: PD55-09
Sources of Funding: None

Introduction

Active surveillance (AS) has gained increased popularity for its role in reducing overtreatment of low-risk prostate cancer. One major concern about AS is the potential for understaging more aggressive disease. Additionally, men on AS are often subject to numerous prostate biopsies which also carries morbidity risk. Multiparametric MRI (mpMRI) of the prostate has demonstrated its ability to better detect clinically significant prostate cancer (CSPC) versus standard TRUS-biopsy alone. Using mpMRI, we aim to determine which men on AS are at risk of being upstaged, and which men could potentially avoid repeat biopsy while safely remaining on AS.

Methods

We reviewed men on AS who underwent mpMRI of the prostate followed by MRI-TRUS (Uronav) fusion biopsy between January 2014 and May 2016. All men had a standard 12-core biopsy simultaneously or within the past 12 months. For this study, CSPC is defined as Gleason score ≥7. Using univariate and multivariate logistic regression analyses, we examined the effect of age, race, PSA, PSA density (PSAD), prostate volume by MRI, PIRADS score, lesion size, number of lesions, and DRE to determine the likelihood of upstaging to CSPC. The multivariate model was selected using Akaike Information Criterion to optimize model parsimony and fit.

Results

A total of 101 men on AS underwent MRI-TRUS fusion biopsy. Patients had a median age of 66.5 years, PSA of 6.5ng/mL, prostate volume of 47.9mL, and PSAD of 0.14. Univariate analysis revealed that PSA, PSAD, increasing PIRADS score, lesion size >2cm, and 3 or more lesions on MRI increased the odds of CSPC. Multivariate logistic regression demonstrated that PSAD ≥0.15 (OR 2.66, CI 1.0-7.03, p=0.049) and increasing PIRADS score (PIRADS 4: OR 10.6, CI 2.1-53, p=0.004; PIRADS 5: OR 15, CI 2.8-80, p=0.002) were independent predictors of CSPC. Men with a PIRADS score of ≥3 with a PSAD ≥0.15 had a 55% chance of being upstaged to CSPC. Conversely, in men with PIRADS score ≤3 with a PSAD <0.15, no upstaging was seen (Figure).

Conclusions

In men on AS, the combination of mpMRI PSAD and PIRADS score predicts upstaging when PIRADS score is ≥3 with a PSA density ≥0.15. When this criteria is not met, men may potentially forgo repeat biopsy while safely maintaining them on AS. Further prospective study is warranted.

Funding

None