Extracapsular extension on multiparametric magnetic resonance imaging better predicts pT3 disease at radical prostatectomy compared to perineural invasion on biopsy.

Introduction: Risk assessment for non-organ-confined prostate cancer (PCa) is important in the surgical planning for radical prostatectomy (RP). Perineural invasion (PNI) on prostate biopsy has been associated with adverse pathological outcomes at prostatectomy. Similarly, the identification of suspected extracapsular extension (ECE) on multiparametric magnetic resonance imaging (mpMRI) has been shown to predict non-organ-confined disease. However, no prior study has compared these factors in predicting adverse pathology at prostatectomy. We evaluated mpMRI ECE and prostate biopsy PNI on multivariable analysis to determine their ability to predict pathological stage at time of RP. Methods: We retrospectively investigated the prostatectomy database at our institution to identify men who underwent prostate biopsy with pre-biopsy mpMRI and subsequent RP from 2013– 2017. Multivariable regression analysis was performed to compare the association of mpMRI ECE (mECE) and PNI on prostate biopsy on the likelihood of finding pT3 disease on pathology post-prostatectomy. Results: Of a total 454 RP between 2013 and 2017, 191 patients met our inclusion criteria. Stage pT2 and pT3+ were found in 120 (62.8%) and 71 (37.2%) patients, respectively. Patients with mECE had 4.84 cumulative odds of worse pathological stage on RP (p=0.045) compared to PNI on biopsy, which showed cumulative odds of 2.25 (p=0.048). When controlling only for those patients without PNI, mECE was still found to be a significant predictor of pT3 disease at RP (p=0.030); however, in patients without mECE, PNI was not significant (p=0.062). Conclusions: While mECE and biopsy PNI were both associated with worse pathological stage on RP, mECE had significantly higher cumulative odds compared to PNI. The significant predictive ability of mECE adds further clinical value to the use of mpMRI in PCa management. While validation in a larger cohort is required, these factors have important clinical implications with regards to early diagnosis of advanced disease and surgical planning.