Timo Soeterik

87 Nerve Sparing and Risk of Positive Margins BACKGROUND Radical prostatectomy (RP) is a treatment modality for localised prostate cancer shown in a prospective randomized trial to significantly increase life expectancy compared with conservative management. 1 Together with radiation therapy, it is one of the most established treatment options for patients with localised prostate cancer and a life expectancy of more than 10 years. 2 Erectile dysfunction and urinary incontinence are unfortunately common consequences of RP that have a severe impact on quality of life, affecting approximately 80% and 20% of patients, respectively. 3,4 Preservation of the neurovascular bundles can potentially decrease the risk of erectile dysfunction and to a lesser extent urinary incontinence. 5, 6 Because the neurovascular bundles are adjacent to the prostate, it is highly possible that nerve sparing increases the risk of positive surgical margins. Although the European Association of Urology guidelines state that nerve bundle preservation is contraindicated in case of tumours with a high risk of extracapsular disease, it is assumed that it can be performed safely in most men with localised disease. 2 A systematic review and meta-analysis confirmed the safety of nerve sparing in patients with localised prostate cancer, as it was not associated with an increased risk of positive margins among patients with pT2 tumours (RR 0.92, 95% CI 0.72 - 1.13). Remarkably, in patients with pT3 disease nerve sparing was even associated with a decreased risk of positive margins (RR 0.83, 95% CI 0.71 - 0.96). 7 However, these results should be interpreted with caution as the observational studies previously performed on this subject were susceptible to selection bias. The available published studies that support current guidelines may have insufficiently accounted for case-mix differences due to patient selection. Therefore, these confounders may have consequently masked the actual association between nerve sparing and the risk of positive margins. Since a positive margin is associated with a higher risk of biochemical recurrence and even cancer specific mortality, 8,9 proper surgical planning for nerve sparing with a minimum risk of positive margins should be undertaken. Given the importance of the issue and the limitations of the previous research, there is a remaining need for studies of higher methodological quality on this subject. Obviously, a randomised controlled trial would be the most methodologically sound approach. However, randomising patients for nerve sparing and non-nerve sparing surgery would not likely be done based on ethical grounds as assignment to non-nerve sparing could be regarded as unnecessarily harmful for patients randomised into the non-nerve sparing arm. As there are several studies reporting the benefits of nerve sparing during RP, these patients will not have the opportunity to retain erectile function. 10 Therefore, the aim of this study is to evaluate the association between nerve sparing RP and the risk of a positive surgical margin by retrospectively analysing a large multicentre patient population, adjusting for a large number of patient-related and prostate side-specific covariates using multivariable regression analysis. 5