A Side-Specific Nomogram for Extraprostatic Extension May Reduce the Positive Surgical Margin Rate in Radical Prostatectomy - Beyond the Abstract

To improve the functional outcome of the radical prostatectomy, nerve-sparing techniques have been introduced.Although nerve-sparing can reduce the risk of erectile dysfunction,2  it is independently associated with an increased risk of positive surgical margins (PSM).3 Since PSM increases the risk of disease recurrence and even cancer-specific mortality, nerve-sparing with an adverse oncological outcome may impair the long-term prognosis.4

The European Association of Urology guidelines advise against nerve-sparing in case of a high risk of extraprostatic extension (EPE).5 In most cases (85%), EPE is only present on one side;6 therefore, contralateral nerve-sparing can be presumed as an oncologically safe option.

The MRI has a high specificity for the detection of EPE (80–85%), its per-prostate sensitivity is low (57%). Therefore, the MRI information alone is unreliable to exclude the presence of EPE7. Hence, a side-specific approach guided by a nomogram that includes MRI parameters is recommended.5,8

Multiple of these side-specific nomograms are developed9-12  but to our knowledge the clinical impact of these nomograms is yet unknown.

The nomogram by Soeterik et al.12  was validated in two centres, of which one our centre, and had an excellent area under the curve (AUC) ranging from 0.77 to 0.83 in the two cohort.

With the aim of assessing the impact of preoperative application of the nomogram. We provided the results of the nomogram to the urological surgeon before 50 RPs. A threshold of 20% was advised to perform nerve-sparing, this advice was not binding. This intervention cohort was compared to the retrospective cohort consecutively operated before the implementation of the cohort.

Our findings are that with the implementation of the nomogram we found a reduction of the amount of PSM’s on lobes with EPE (OR 0.18 95% CI 0.03, 0.77, p = 0.029), with overall the same amount of nerve-sparing performed in the two groups.

Limitation includes, that our hospital was one of the validation cohorts for the nomogram explaining the excellent results and may make the results less generalizable. Furthermore, the 20% threshold was advised but not binding to the surgeon. Lastly, we did not correct for surgeon experience, as this would result in small patient groups.

Concluding, a side-specific approach toward the prediction of EPE using a nomogram result in comparable rates of nerve-sparing but lower rates of PSMs on the side of histological EPE. Applying a side-specific nomogram may help counselling patients for nerve-sparing without compromising the oncological outcome.

Written by: Joris Heetman, Department of Urology, Sint Antonius Hospital, Utrecht-Nieuwegein, The Netherlands

References:

  1. Walsh PC. The discovery of the cavernous nerves and development of nerve sparing radical retropubic prostatectomy. J Urol 2007;177:1632–5. https://doi.org/10.1016/j.juro.2007.01.012.
  2. Nguyen LN, Head L, Witiuk K, Punjani N, Mallick R, Cnossen S, et al. The Risks and Benefits of Cavernous Neurovascular Bundle Sparing during Radical Prostatectomy: A Systematic Review and Meta-Analysis. J Urol 2017;198:760–9. https://doi.org/10.1016/j.juro.2017.02.3344.
  3. Soeterik TFW, van Melick HHE, Dijksman LM, Stomps S, Witjes JA, van Basten JPA. Nerve Sparing during Robot-Assisted Radical Prostatectomy Increases the Risk of Ipsilateral Positive Surgical Margins. J Urol 2020;204:91–5. https://doi.org/10.1097/JU.0000000000000760.
  4. Morizane S, Yumioka T, Makishima K, Tsounapi P, Iwamoto H, Hikita K, et al. Impact of positive surgical margin status in predicting early biochemical recurrence after robot-assisted radical prostatectomy. Int J Clin Oncol 2021;26:1961–7. 
  5. Mottet N, van den Bergh RCN, Briers E, Van den Broeck T, Cumberbatch MG, De Santis M, et al. EAU-EANM-ESTRO-ESUR-SIOG Guidelines on Prostate Cancer-2020 Update. Part 1: Screening, Diagnosis, and Local Treatment with Curative Intent. Eur Urol 2021;79:243–62. 
  6. Ohori M, Kattan MW, Koh H, Maru N, Slawin KM, Shariat S, et al. Predicting the presence and side of extracapsular extension: a nomogram for staging prostate cancer. J Urol 2004;171:1844–9; discussion 1849. https://doi.org/10.1097/01.ju.0000121693.05077.3d.
  7. de Rooij M, Hamoen EHJ, Witjes JA, Barentsz JO, Rovers MM. Accuracy of Magnetic Resonance Imaging for Local Staging of Prostate Cancer: A Diagnostic Meta-analysis. Eur Urol 2016;70:233–45.
  8. Sighinolfi MC, Rocco B. Re: EAU Guidelines: Prostate Cancer 2019. Eur Urol 2019;76:871.
  9. Martini A, Gupta A, Lewis SC, Cumarasamy S, Haines KG, Briganti A, et al. Development and internal validation of a side-specific, multiparametric magnetic resonance imaging-based nomogram for the prediction of extracapsular extension of prostate cancer. BJU Int 2018;122:1025–33. https://doi.org/10.1111/bju.14353.
  10. Nyarangi-Dix J, Wiesenfarth M, Bonekamp D, Hitthaler B, Schütz V, Dieffenbacher S, et al. Combined Clinical Parameters and Multiparametric Magnetic Resonance Imaging for the Prediction of Extraprostatic Disease-A Risk Model for Patient-tailored Risk Stratification When Planning Radical Prostatectomy. Eur Urol Focus 2020;6:1205–12. https://doi.org/10.1016/j.euf.2018.11.004.
  11. Wibmer AG, Kattan MW, Alessandrino F, Baur ADJ, Boesen L, Franco FB, et al. International Multi-Site Initiative to Develop an MRI-Inclusive Nomogram for Side-Specific Prediction of Extraprostatic Extension of Prostate Cancer. Cancers 2021;13:2627. https://doi.org/10.3390/cancers13112627.
  12. Soeterik TFW, van Melick HHE, Dijksman LM, Küsters-Vandevelde H, Stomps S, Schoots IG, et al. Development and External Validation of a Novel Nomogram to Predict Side-specific Extraprostatic Extension in Patients with Prostate Cancer Undergoing Radical Prostatectomy. Eur Urol Oncol 2020:S2588-9311(20)30133-4.
Read the Abstract