Evaluation of Oncological Outcomes and Data Quality in Studies Assessing Nerve-sparing Versus Non-Nerve-sparing Radical Prostatectomy in Nonmetastatic Prostate Cancer: A Systematic Review

Abstract

CONTEXT: Surgical techniques aimed at preserving the neurovascular bundles during radical prostatectomy (RP) have been proposed to improve functional outcomes. However, it remains unclear if nerve-sparing (NS) surgery adversely affects oncological metrics. OBJECTIVE: To explore the oncological safety of NS versus non-NS (NNS) surgery and to identify factors affecting the oncological outcomes of NS surgery. EVIDENCE ACQUISITION: Relevant databases were searched for English language articles published between January 1, 1990 and May 8, 2020. Comparative studies for patients with nonmetastatic prostate cancer (PCa) treated with primary RP were included. NS and NNS techniques were compared. The main outcomes were side-specific positive surgical margins (ssPSM) and biochemical recurrence (BCR). Risk of bias (RoB) and confounding assessments were performed. EVIDENCE SYNTHESIS: Out of 1573 articles identified, 18 studies recruiting a total of 21 654 patients were included. The overall RoB and confounding were high across all domains. The most common selection criteria for NS RP identified were characteristic of low-risk disease, including low core-biopsy involvement. Seven studies evaluated the link with ssPSM and showed an increase in ssPSM after adjustment for side-specific confounders, with the relative risk for NS RP ranging from 1.50 to 1.53. Thirteen papers assessing BCR showed no difference in outcomes with at least 12 mo of follow-up. Lack of data prevented any subgroup analysis for potentially important variables. The definitions of NS were heterogeneous and poorly described in most studies. CONCLUSIONS: Current data revealed an association between NS surgery and an increase in the risk of ssPSM. This did not translate into a negative impact on BCR, although follow-up was short and many men harbored low-risk PCa. There are significant knowledge gaps in terms of how various patient, disease, and surgical factors affect outcomes. Adequately powered and well-designed prospective trials and cohort studies accounting for these issues with long-term follow-up are recommended. PATIENT SUMMARY: Neurovascular bundles (NVBs) are structures containing nerves and blood vessels. The NVBs close to the prostate are responsible for erections. We reviewed the literature to determine if a technique to preserve the NVBs during removal of the prostate causes worse cancer outcomes. We found that NVB preservation was poorly defined but, if applied, was associated with a higher risk of cancer at the margins of the tissue removed, even in patients with low-risk prostate cancer. The long-term importance of this finding for patients is unclear. More data are needed to provide recommendations.