SUO 2018: Debate: Enucleo-Resection vs. Wedge Resection for Partial Nephrectomy in 4 cm tumors

Phoenix, Arizona (UroToday.com) Dr. Finelli summarized several key points on why enucleation should not be used as the standard of care for partial nephrectomy. He started his talk presenting a case of a 56 year old man with morbid obesity and no family history of cancer, who was found to have a left renal mass. Ct scan showed an exophytic 3.9 cm enhancing mass arising from the lower pole of the left kidney. This patient then underwent a renal mass biopsy, which is commonly performed in the Princess Margaret Cancer, in Toronto. The biopsy revealed renal cell carcinoma, clear cell type with focal rhabdoid differentiation, Fuhrman grade 4, with focal tumor necrosis. The patient also underwent complete metastatic workup which was negative.

Dr. Finelli presented the reasons for supporting enucleation of this type of tumor. These include parenchyma preservation, avoidance of complications, and safety. Dr. Finelli rightfully stated that when we cannot decide whether radical nephrectomy truly causes harm, discussion of a 1-2 mm margin vs. no margin during partial nephrectomy is somewhat unexciting. When assessing the complication rate, data has shown that there is no difference in the blood loss, positive margins rate, urine leak, blood transfusion, major complications, renal function, recurrence, or survival, between enucleation and excision¹. Finally, the issue of safety of enucleation was discussed. Dr. Finelli presented a study of 82 kidneys treated with radical nephrectomy for a tumor <4 cm. In this study, following radical nephrectomy. step sectioning was performed at 3 mm intervals. Amazingly, 31.7% of kidneys were lacking fully intact pseudocapsules, and even more, interestingly, 19.5% demonstrated to have cancer beyond the pseudo capsule! with 12.2% showing a tumor entering normal parenchyma, 2.4% entering a venule, and 4.9% being a satellite tumor. This high percentage of cancer beyond the pseudocapsule has also been shown in another study³.

Incorporating these data together, Dr. Finelli concluded that there are no good reasons to enucleate small renal tumors. Furthermore, the safety of enucleation data is dominated by low-grade cohorts and follow-up of fewer than 5 years. It is also important to remember that positive surgical margins rates increase recurrence rates by 10%^4,5.

Dr. Finelli concluded his concise and elegant talk, stating that enucleation is common (even when not intended). The deliverables of enucleation are unclear and debatable. Lastly, the risk of enucleation is very clear and significantly raises the rate of positive surgical margins. Therefore, rather than debate which surgical approach to applying to small renal masses, partial nephrectomy should be personalized and driven by imaging, clinical scenario, and renal biopsy information.

Presented by: Antonio Finelli, MD, FRCSC, MSc, Princess Margaret Cancer Center, Toronto, Ontario, Canada

References:
1. Mukkamal A et al. Urology 2014
2. Li et al. European Urology 2003
3. Snarskis C. et al. J Urol 2017
4. Bernhard JC et al. Eur Urol 2010
5. Khalifeh A et al. J Urol 2013

Written by: Hanan Goldberg, MD, Urologic Oncology Fellow, SUO, University of Toronto, Princess Margaret Cancer Centre, @GoldbergHanan, at the 19th Annual Meeting of the Society of Urologic Oncology (SUO), November 28-30, 2018 – Phoenix, Arizona

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