Clinical Findings and Treatment Outcomes in Patients with Extraprostatic Extension Identified on Prostate Biopsy

Katherine Fleshner, Melissa Assel, Nicole Benfante, Justin Lee, Andrew Vickers, Samson Fine, Sigrid Carlsson, James Eastham

To describe the histopathological, clinical and imaging findings among men with extraprostatic extension (EPE) on prostate biopsy. We searched our Institutional Pathology Database, between the years 2004-2015, for pathology reports detailing EPE on prostate biopsy in untreated patients. Patient characteristics, biopsy features, imaging interpretations and outcomes were examined. Of 19,950 patients with prostate cancer on biopsy, 112 had EPE, a prevalence of 0.6% (95% CI 0.5%-0.7%). Most patients had palpable, high-grade (Gleason score 9), high-volume, disease classified as high-risk (30%; 34/112), locally advanced (15%; 17/112), or metastatic (35%; 39/112). Most had one or two cores with EPE, typically at the base and with concomitant perineural invasion. EPE was identified by MRI in 80% (32/40). The median follow-up for those who did not die was 1.3 years (IQR 0.3, 4.2). Outcomes for the subgroup of 24 men who had an RP were consistent with high risk disease: positive margins (58%; 14/24), SVI (42%; 10/24), and LNI (46%; 11/24). For the entire cohort, the 3-year risks of metastasis and overall mortality were 32% (95% CI 22%, 44%) and 37% (95% CI 27%, 50%), respectively. We did not find evidence to suggest that the proportion of cores with cancer that also had EPE was associated with overall mortality (p=0.09). EPE is a rare finding on prostate biopsy. It is strongly associated with other features of aggressive prostate cancer.