Elsevier

European Urology

Volume 55, Issue 6, June 2009, Pages 1410-1418
European Urology

Kidney Cancer
Histopathologic Analysis of Peritumoral Pseudocapsule and Surgical Margin Status after Tumor Enucleation for Renal Cell Carcinoma

https://doi.org/10.1016/j.eururo.2008.07.038Get rights and content

Abstract

Background

The oncologic safety of blunt tumor enucleation (TE) of renal cell carcinoma (RCC) depends on the presence of a continuous pseudocapsule (PS) around the tumor and on the possibility of obtaining negative surgical margins (SMs).

Objective

To investigate the PS and SMs after TE to define the real need to take a rim of healthy parenchyma around the tumor to avoid the risk of positive SMs. The risk of PS invasion related to other clinical and pathologic variables was also evaluated.

Design, setting, and participants

Between September 2006 and December 2007, data were gathered prospectively from 187 consecutive patients who had kidney surgery. Overall, 90 consecutive patients who had TE for RCC were eligible for the study. All specimens were evaluated using an image analyzer by a dedicated uropathologist.

Intervention

TE was done by blunt dissection using the natural cleavage plane between the tumor and the normal parenchyma.

Measurements

PS, SM, and routinely available clinical and pathologic variables were recorded.

Results and limitations

In 60 RCC tumors (67%) the PS was intact and free from invasion (PS−) while in 30 (33%) there were signs of penetration within its layers, with or without invasion beyond it. Indeed, 26.6% had PS that had been penetrated on the parenchymal side and 6.6% had penetration on the perirenal fat tissue side. The odds of having PS penetration increased significantly with an increase in clinical tumor size. PS penetration was also significantly associated with pathologic tumor dimensions and grade. In all cases the SMs were negative after TE. The present patients, followed for >2 yr, will enable us to correlate the risk of local recurrence with PS status.

Conclusions

The risk of PS penetration is associated with clinical and pathologic tumor dimensions and grade. If there is PS invasion into normal parenchyma, the presence of a thin layer of tissue allows for negative SM even if a TE is performed.

Introduction

Nephron-sparing surgery (NSS) has been widely accepted since the early 1980s [1], [2] as an elective procedure for treating single sporadic renal tumors. Several studies have shown this procedure to offer equally effective local control and a similar disease-specific survival rate compared to radical nephrectomy (RN) for treating renal-cell carcinoma (RCC) tumors of <4 cm in their greatest dimension [1], [2], [3], [4]. Moreover, recent reports have shown that NSS achieves local tumor control equivalent to RN also for RCC of 4–7 cm [5], [6].

The concern about local recurrence due to inadequate tumor excision and the reported risk of pseudocapsule (PS) invasion on the parenchymal side [7], [8], [9], [10], [11] led most surgeons to remove a minimal rim of normal-appearing parenchyma around the tumor, and at present this is considered to be the technique of choice in patients undergoing NSS [1], [2]. Nevertheless, in recent years there have been several reports on the reduction of the thickness of the safety margins that should be excised with the tumor to avoid the risk of local recurrence. Others have recently gone further, concluding that, if the tumor is completely excised, the width of the resection margin is irrelevant and not correlated with disease progression, thus providing an intriguing insight into the real need to excise an adequate rim of healthy kidney tissue around the tumor [11], [12], [13], [14], [15].

The tumor enucleation (TE) technique, which consists of excising the tumor by blunt dissection without a visible rim of normal parenchyma, has been reported in the treatment of benign-looking tumors such as angiomyolipomas. But only a few studies in the 1980s and early 1990s reported on the use of this technique for treating small RCC tumors, and they showed similar 5-yr survival rates to those of partial nephrectomy [16], [17], [18], [19]. Recently, other retrospective analyses confirmed that TE can be safely used for treating pT1a–pT1b RCC tumors, and it is not associated with any greater risk of local recurrence than is partial nephrectomy [20], [21], [22], [23]. Therefore, the discrepancy between the optimal oncologic results of in vivo TE reported in several recent retrospective analyses [20], [21], [22], [23] and the pathologic concerns of incomplete tumor excision based on data obtained by studies after an ex vivo TE or tumor sections of RN specimens remains an unsolved oncologic issue in conservative kidney surgery [8], [9], [10], [11].

The objective of this prospective study was to investigate the existence, integrity, possible invasion of peritumoral PS and surgical margin (SM) status after NSS, performed as TE for the treatment of RCC, with the aim of characterizing PS in RCC and defining the real need to take a rim of healthy parenchyma around the tumor to avoid the risk of a positive SM.

Section snippets

Methods

Between September 2006 and December 2007, data were gathered prospectively from 187 consecutive patients who had kidney surgery. Overall, 104 (55.6%) had a conservative treatment, TE, while 83 (44.4%) had RN. All but one NSS were successful; in one case with imperative indications for a 4-cm tumor, we decided to convert to RN for the intraoperative detection of intrarenal vein thrombosis after TE. The pathologic evaluation in this case confirmed the presence of renal vein thrombosis (pT3b). No

Results

At diagnosis, 87 of the 104 tumors (84%) were detected incidentally in asymptomatic patients while 17 (16%) were associated with either microscopic or frank hematuria with or without flank pain. Overall, 95 patients were treated with elective TE (91%) while 9 patients received TE for imperative indications (9%).

All patients with histologically confirmed RCC were eligible for the study (90/104, 86.5%), and the 14 who had NSS for histologically confirmed benign tumors were excluded (13.5%). At CT

Discussion

To avoid the risk of local recurrence, the excision of a minimal and visible margin of normal-appearing parenchyma around the tumor is considered the standard surgical technique of NSS [2].

Nevertheless, whether or not to excise a rim of healthy parenchyma, theoretically necessary to avoid the risk of a positive SM and local recurrence, is a matter of great controversy, and recent reports concluded that the width of the resection margins does not correlate with disease progression and that if

Conclusions

The PS can be infiltrated with or without invasion beyond it in patients undergoing conservative surgery, and the risk of PS invasion is statistically associated with clinical and pathologic tumor dimensions and nuclear grade. If there is PS penetration and invasion beyond it, the presence of a thin layer of parenchymal tissue allows for negative SM even if no efforts are made to leave a rim of healthy kidney tissue around the neoplasm. Our data clearly represent a rationale for adopting the TE

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