Is Simple Enucleation a Minimal Partial Nephrectomy Responding to the EAU Guidelines’ Recommendations?

The objective of nephron-sparing surgery (NSS) isthe complete removal of the tumor while preservingthe largest possible part of healthy renal paren-chyma. Once reserved to patients with a single(anatomical or functional) kidney or bilateral renalneoplasms (imperative NSS), NSS is currentlyconsidered the gold standard for tumors 4cm(T1a) also in patients with a contralateral normalkidney [1]. In this category of patients, in compar-ison to radical nephrectomy, open NSS provokes anonsignificant increase of perioperative complica-tions[2]whileitgivesoverlappingresultsintermsofcause-specific survival [3,4].A recent literature review demonstrated that1–6% of patients undergoing open or laparoscopicNSS present a local recurrence requiring a new localtreatment during follow-up [5]. In this cases, localrelapse can be attributed to residual tumor at thesurgical margin due to inadequate tumor resection,multicentricity of renal cell carcinoma (RCC) withconcomitant undetectable satellite lesions or newonset malignant lesions.With the objective of reducing the risk of localrecurrencesduetoincompleteresections,forseveralyears the standardsurgical technique of NSS forRCCinvolves excising an additional 1-cm margin ofperitumor renal parenchyma to ensure a truenegative margin and to decrease this risk of localrecurrence [6–9]. The extension of such a safetymargin,arbitrarily introduced by Vermooten in 1950,has been questioned in the last years, particularlyconsidering the widening use of NSS. Indeed,removing a 1-cm safety margin can make NSS morecomplex in several cases, causing an increasingmorbidity (urinary collecting system injuries, needto clamp renal vessels, prolonged ischemia times,higherrisksforbleeding,andpotentialinjurytohylarvessels). Moreover, the resection of a thick safetymargin might reduce the preserved parenchyma,negatively affecting the renal function of patientswith bilateral tumors or a single kidney.In the last years, some authors have demon-strated that negative surgical margins can beachieved also reducing the safety margin to 5mm[10–13]. In recent series, the mean thicknessof the safety margin surrounding the tumor was2.5 mm [11] to 5 mm [13] but with minimum valuesranging between 0 mm and 1 mm and maximumvalues ranging between 7 mm and 23 mm, respec-tively (Table 1). Specifically, the safety marginranges between 4 mm and 10 mm at the area ofthe renal capsule and is reduced to 0–6 mm at thebottom of the tumor [14,15]. It is possible tohypothesize that the variability of the thickness ofthe safety area around the tumor might be influ-enced by several anatomopathologic features suchas the peripheral or intraparenchymal location ofthe neoplasia, its more or less spherical shape, the