The impact of multifocal perineural invasion on biochemical recurrence and timing of adjuvant androgen-deprivation therapy in high-risk prostate cancer following radical prostatectomy.

Abstract

e595 Background: Perineural invasion (PNI) is a distinct pathologic entity and a recognized source of tumor spread. However, the role of PNI in high-risk prostate cancer (PCa) has not been explored. We investigated the impact of the severity of PNI on biochemical recurrence (BCR) and optimal timing of adjuvant androgen deprivation therapy (ADT) post radical prostatectomy (RP). Methods: Of 265 prostatectomies, median follow-up 45 months, were assessed for the presence of PNI and its intensity (unifocal PNI and multifocal PNI) in RP specimen. Kaplan-Merier curves were used to estimate BCR probabilities. Cox proportional hazard models were used to address predictors of BCR. Harrell’s C-index was conducted to further validate prognostic value of multi-PNI. Results: A total of 123 patients (46.4%) were PNI positive, among which, 91 (74%) and 32 (26%) had unifocal PNI (uni-PNI) and multifocal PNI (multi-PNI), respectively. Other than uni-PNI, the presence of multi-PNI was strongly associated with increasing incidence of BCR (HR = 3.87, 95% CI: 1.66-9.01, p = 0.002). Patients with uni-PNI seemed to have a similar BCR rate to those without PNI after adjuvant ADT. For men with multi-PNI, immediate ADT obviously appeared to be superior to delayed ADT in decreasing biochemical failure. Conclusions: Multi-PNI detected in high-risk RP specimens could be a prognosticator for early biochemical relapse post-surgery. Our findings suggest that patients with multi-PNI appear appropriate to choose adjuvant therapy as soon as possible after surgery.