EAU 2019: Impact of Bilateral Neurovascular Bundle Preservation on Oncological Outcomes in Non-organ Confined Prostate Cancer Patients

Barcelona, Spain (UroToday.com) Sparing of the neurovascular bundle (NVB) at the time of radical prostatectomy (RP) has been established as a predictor of improved functional recovery, particularly as it relates to erectile function. However, sparing the NVB entails a closer dissection to the prostatic capsule, which may carry the risk of positive surgical margins, especially in more locally advanced tumors.   For this region, most surgeons avoid sparing the NVB in men with known extraprostatic extension (pT3a) disease – and pre-operative staging studies can help guide that decision.

However, in men without known locally advanced disease prior to RP, nerve sparing (NS) may still be completed. In this study, the authors from two high volume centers in Europe evaluate the oncologic safety of NVB preservation in patients with pathological non-organ confined PCa at RP. This is a retrospective analysis, with its inherent biases. The authors identified patients who harbored pathologic T3 stage with bilateral or no NVB preservation at RP (single NS was not included), between 2000 and 2015. Only patients with Gleason grade group 3 or higher in the RP specimen and without lymph node invasion were included. These patients represented a higher risk cohort most likely to harbor pT3 disease and develop recurrence in the short term.
  • Importantly, patients underwent NS at the discretion of the treating surgeon
  • At the Martini Klinic, frozen sections are taken at the time of resection – if positive, NS is abandoned – and these patients are excluded from this analysis.
  • At the University of Montreal, surgeons use clinical characteristics to guide NS
  • Dr. Prasser noted that pre-operative staging studies may have been used, but were not used uniformly across all patients
Propensity score weighting for the inverse probability of treatment (IPTW) was used to reduce the effect of selection bias. Kaplan-Meier analyses and multivariable Cox regression models tested the effect of NVB preservation on biochemical recurrence (BCR) and clinical recurrence (CR).

Of the 1,460 patients identified, 53.4% (780) underwent bilateral NVB preservation while the remainder had no NS – at the discretion of the treating physician.

When comparing the two groups, patients with bilateral NVB preservation had: lower surgical margin rate (33.8 vs. 46.8%, p<0.001) and less frequently harbored pathologic stage T3b (34.7 vs. 47.5%, p<0.001). This would suggest that they were selected out better for NS, but a significant portion still had PSM and pT3b disease. Full demographics shown below:
EAU 2019 descriptive characteristics PCa

Median BCR-free survival after RP was 58.4 vs. 62.9 months (p=0.18), CR-free survival rates at 120 months (median not reached) were 76.9 and 71.9% (p=0.33) for bilateral and no NVB preservation, respectively.

On multivariable Cox regression models, after IPTW, NVB preservation was not an independent risk factor of BCR (p=0.7) or CR (p=0.7).

EAU 2019 PCa pts treated with RP

As can be expected, pT3b stage, year of surgery (and therefore experience), GG5 disease, PSM and RT / ADT use were predictors of BCR and CR.

Therefore, despite some selection bias, it would appear from this series that NS of bilateral NVB was not associated with worse oncologic outcomes – if appropriately selected. However, the article doesn’t comment on patient selection nor does it touch on unilateral NS. Knowing that patients at the Martini Klinik were selected out using frozen sections, perhaps this should be considered. Further data is required.

Presented by: Felix Preisser, MD, University Hospital Frankfurt, Dept. of Urology, Frankfurt, Germany

Written by: Thenappan Chandrasekar, MD, Clinical Instructor, Thomas Jefferson University, twitter: @tchandra_uromd, @TjuUrology at the 34th European Association of Urology (EAU 2019) #EAU19, conference in Barcelona, Spain from March 15-19, 2019.