Introduction

Pathologic progression is identified in >25% of prostate cancer (CaP) patients on active surveillance (AS). Yet, the ability to identify which patients are at risk for progression is limited to PSA-based biomarkers with variable utility. Multiparametric MRI (mpMRI) with fusion-guided prostate biopsy (FBx) has demonstrated utility in risk stratification for patients considering AS. We compared mpMRI characteristics with PSA kinetics for the prediction of pathologic progression in patients on AS.

Methods

A review of men on AS with serial mpMRI and 2 or more FBx sessions was performed. FBx sessions consisted of targeted biopsies and a 12-core systematic biopsy. Men who met NIH Expanded AS criteria included those with low and intermediate risk CaP, Gleason score ? 3+4 with no restriction on percent core involvement. Progression was defined by patients with initial Gleason 3+3 to any Gleason 4, and Gleason 3+4 to a primary Gleason 4 or higher. MRI progression was defined as increase in lesion suspicion score, size, or new lesion on follow-up. PSA density (PSAD) > 0.15ng/ml², velocity (PSAV) > 0.75ng/ml/year, doubling time (PSAdt) < 3 years, and imaging characteristics were examined for association with pathologic progression at surveillance biopsy.

Results

A total of 178 men were included for analysis. Median follow-up was 19 months [IQR 14-29]. Median age, PSA, and prostate volume of our cohort were 63 years [IQR 58-68], 5.0ng/ml [IQR 3.4-7.4] and 47.8ml [IQR 36.4-59.7] at enrollment. The sensitivity and specificity of predicting pathologic progression by mpMRI, PSAD, PSAV and PSAdt were 46% and 65%, 16% and 88%, 20% and 87%, and 30% and 75% respectively. A combination of MRI with PSAD, PSAV, or PSAdt yielded a sensitivity and specificity of 53% and 44%, 57% and 57%, or 63% and 49% respectively. Using a decision curve analysis, mpMRI offers a small additional benefit for predicting CaP progression.

Conclusions

MpMRI alone marginally outperforms PSA kinetics for predicting pathologic progression in men on AS for CaP. The combination of mpMRI with PSA parameters increases the sensitivity of identifying progression in AS patients, but still fails to capture a significant proportion of progression. Further research in prostate imaging and other biomarkers will be needed to more accurately risk stratify AS patients.

Funding

This research was supported by the Intramural Research Program of the National Cancer Institute, NIH