Introduction

Partial nephrectomy (PN) is an established curative approach for the treatment of patients with small renal masses (SRMs) (≤4 cm) [1–4]. It can be performed for selected tumours with a maximum diameter of 7 cm in centres with experience [5–10]. Moreover, the benefits of PN are well established and include, above all, a decreased risk of long-term renal insufficiency and consequently a positive impact on the quality of life [11–13].

In the last few years, laparoscopic partial nephrectomy (LPN) has gained more importance in the treatment of SRMs, and in some centres it has become the “first-choice treatment” as it is able to duplicate the principles of open partial nephrectomy (OPN) adding the advantages of mini-invasiveness [14–16].

While the role of LPN for SRMs is well documented, literature is poor for LPN for large masses (more than 4 cm). To give a contribution on this topic, we designed this survey, and we reviewed the experience of six European laparoscopic centres for LPN for renal masses from 4 to 7 cm in order to evaluate the role of this procedure in the treatment of this kind of mass.

Patients and methods

Data collection

Our database was sent to 15 highly experienced laparoscopic urological centres, and data concerning their LPN for renal masses up to 7 cm of diameter were requested. Patients’ data were extracted from each institutional database to obtain information only for those LPN performed for 4–7 cm masses, according to computed tomography (CT) scans. Inclusion criteria were the same in all centres: a single, organ-confined, contrast-enhancing renal mass. Exclusion criteria included renal vein involvement, lymphadenopathy, or extrarenal tumour extension.

Demographic and radiological features of the lesions were recorded. Based on a previously reported classification [17], tumour growth pattern was defined as central when tumour involved the central sinus fat or the collecting system on pre-operative computed tomography (CT) scan; as cortical when the lesions seemed to involve only the renal cortical at CT scan, and cortico-medullar when the lesions involved the medulla too.

The following variables were also reported.

Intraoperative data: surgical access, type of tumour resection (pure enucleation, enucleo-resection, wedge resection), estimated blood loss, type of vascular clamping (artery or artery and vein), WIT (starting from the clamping to the declamping of vessels), operative time, type of suture (running or interrupted), collecting system repair, use of biological glue, intraoperative complications. Intraoperative haemorrhage was defined as bleeding necessitating transfusion during the procedure, as required by the anaesthesiologists.

Post-operative data: complications which have been classified according to Clavien System [18] and subsequent treatment, post-operative hospital stay.

Pathological data: the pathologist of each Centre evaluated the surgical specimen. Tumour histology was reported; malignant tumour were classified according to World Health Organization (WHO) 2004, graded according to Fuhrman grade and staged according to 2002 Union International Contre le Cancer (UICC) revised TNM classification [19]. Data from surgical margins (positive or negative) were also collected. No frozen section analyses were reported.

In case of missing data, analyses were performed considering the available information and specifying the number of patients involved.

Statistical analyses

All data were processed through statistical software. Descriptive analysis was used to evaluate all considered variables, qualitative analyses were compared by using X 2 (Fisher exact tests), and quantitative analyses were compared by using Student’s t-test. Multiple regression analysis was used to evaluate risk factors for complications and for positive surgical margins, blood losses, Spearman R test was used to investigate correlation between WIT and lesion size.

In all analyses, the differences were considered statistically significant when P < 0.05.

Results

This study includes all patients who underwent LPN from January 2002 to September 2008 in the six Urological Centres which answered our request. The overall number of LPN was 450 performed in six centres. In 63 patients (14%), the procedure was performed for large tumour (>4–7 cm).

The number of procedures from each institution was 24 (38.2%) from Orbassano—Torino (Italy); 22 (35%) from Bordeaux (France); 5 (7.9%) from Milano (Italy); 5 (7.9%) from Roma—Italy; 4 (6.3%) from Basel (Switzerland); and 3 (4.7%) from Linz (Austria). In each centre, a single surgeon performed all the procedures.

Demographic data and tumour characteristics are reported in Table 1.

Table 1 Demographic data and tumour characteristics
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Procedures and morbidity

Operative data are summarized in Table 2. In all patients, an intraoperative ultrasonography with laparo-endoscopic probe was performed, and enucleo-resection (tumour excision with removal of peri-tumoural healthy tissue) was also performed, and the renal artery was clamped from the beginning of tumour resection to the end of the parenchymal suture. No frozen sections were performed during the procedure.

Table 2 Operative data
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In 8 patients (12.7%) WIT was longer than 30 min. At statistical analyses, no correlation was recorded between WIT and lesion size (P > 0.05) nor between WIT, side, location, growth pattern, type of suture or urinary tract repair. Hypothermia was not used in any patient.

Complete data on complications were available for 41 patients; Table 3 shows details of complications and their management. Intraoperative complications were recorded in 3 (7.3%) patients; in all patients bleeding occurred requiring conversion to open surgery but without the need of nephrectomy. Post-operative complications were recorded in 11 (26%) patients. Comparing this subgroup (14/41) with patients without complications (27/41), a significant difference was recorded in terms of pathological lesion size (4.9 vs. 4.4 cm, P = 0.048); moreover, a higher number of patients with cortico-medullar lesion was recorded in the first subgroup (P = 0.02). Multiple regression analyses confirmed the correlation between overall complications and tumour size (P = 0.04).

Table 3 Post-operative complications
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Pathological data

Pathological data are summarized in Table 4. Focal positive margins were found in 3/46 patients with malignant tumours (6.5%), and in all patients this occurred in cortico-medullar tumours. No tumour violation was recorded. In three patients (6.5%), tumour size was slightly greater than that evaluated by CT scans.

Table 4 Pathological data
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Multiple regression analyses did not reveal correlations between surgical margin status and tumour side, size, and location or growth pattern (P > 0.05).

Discussion

Laparoscopy has been widely used in the last decade for many urological diseases, and LPN is performed for peripheral SRMs in some centres [14–17]. On the other hand, whilst some surgeons expanded from 4 to 7 cm the size limit for OPN with excellent results, few large masses have been removed by LPN [20–27].

In order to further clarify the role of LPN for large tumours, we designed a survey involving European centres in which LPN is currently used for the treatment of renal masses.

To our knowledge, this is one of the largest series of LPN for tumour 4–7 cm in size. We have chosen cut-off size of 7 cm based on CT scans in order to include (in case of RCC) only clinical T1b stage.

Intra-operative data were comparable to those reported in literature for LPN for SRMs and for OPN and LPN for large masses [3, 8, 16, 27].

As far as renal vessels clamping and WIT are concerned in all cases, the sole renal artery was clamped from the beginning of tumour resection to the end of parenchymal suture. Nguyen et al. [26] has suggested removing the clamp before the end of renal suture in order to reduce the WIT; nevertheless, in our opinion, this technique makes suturing more difficult and can contribute to significant bleeding. We recorded a mean WIT of 25.7 min, and our data confirm that WIT during LPN is longer than during OPN. These aspects could be considered a potential advantage for OPN [3, 8]. In spite of this, one should note that WIT in the present series is comparable to that reported by many others during LPN for SRMs [14, 16, 17]. This aspect could be related to patient selection: we have not treated central lesions and all patients had elective indications. With the aim to reduce the kidney damage related to WIT, some proposed hypothermia during LPN [28, 29]. Few cases (<30) have been reported, and operative techniques are tricky and time-consuming; perhaps for these reasons, none of the surgeons involved in this survey used this approach. Nevertheless, when a large mass has to be treated and long ischemia times are supposed, this approach should be considered.

Unfortunately, we were unable to retrieve data on perioperative complications in one of the centres limiting our evaluations of this aspect to 41 cases. This could make our data less reliable. We recorded significant complications (Clavien system grade > III) in 14% cases, and we believe that our complication rate is acceptable for this kind of surgery, and this is comparable to those reported for LPN for SRMs, LPN and OPN for large masses, even though one should note that complication rate of OPN in recent series is relatively low [8, 10, 14–17, 21, 27].

Our data confirm that bleeding is the most frequent complication during LPN, while urinary fistula is a rarer event. We point out that statistical analyses identified lesion size as a risk factor for overall complications (P = 0.04), and this suggests that other studies are required in order to identify a “safety cut-off” size.

Our data show that cortico-medullar lesions increased significantly the chance of complications. This suggests that the surgeon should be cautious in treating this kind of lesion laparoscopically and should offer this approach especially when a cortical lesion has to be treated.

As far as pathology is concerned, surgical margins were positive in 3 (6.5%) patients. In all cases, a focal (microscopic) interruption of normal renal parenchyma was recorded, but in no case violation of tumour was recorded. Due to these pathological characteristics, no further therapies were required, and a close follow-up was scheduled for these patients. This rate is greater than that reported after OPN, but it is comparable to those reported in the already cited recent series of LPN [16, 27]. All positive margins were recorded for cortico-medullar lesions, while no positive surgical margins were found for cortical tumours. These data, even if not statistically significant, suggest that cortical lesions were removed more effectively.

As far as RCC is concerned, when considering data about surgical margins and data about complications, we advise that cortical rather than cortico-medullar lesion should be treated with laparoscopic approach.

We did not report data concerning the follow-up of the patients, basically because of our follow-up is too short to give helpful information. Intermediate-term oncological outcomes will be reported in a further analysis for this cohort.

This survey has some limitations. First, due to its retrospective character, some information was missing. Six different surgeons and difference in centre “volume”, which are crucial points in this kind of surgery, could affect the results. Even if the lack of central pathology review could be an adjunctive limitation, one should note that each centre has an uro-pathologist experienced in kidney cancer, and this has warranted a homogeneous evaluation of specimen.

Although these limitations could affect the results, we believe that this study can give a useful message to the urological community. Our data suggest LPN could be an emerging for the treatment of the large tumours, particularly for cortical tumours. We observed a slight increase in both morbidity and WIT, in comparison with OPN, while no difference was noted in comparison with LPN data available in literature for small and large masses. Since complication rate is not negligible also in skilled hands, a significant laparoscopic experience is mandatory before embarking on LPN for large mass. Nevertheless, one should note that this is an initial experience, and further improvements will be observed for LPN for large lesions too, as usually happens with new techniques or extended indications.

Finally, we would like highlight as when a large renal mass has to be treated and the surgeon is not skilled in LPN, a well-performed OPN is better than a poor LPN or a well-performed laparoscopic radical nephrectomy.

In conclusion, this survey confirms that LPN for tumours 4–7 cm in size is feasible in experienced hand. WIT and complication rate are still questionable points, and further studies are required in order to better clarify the role of LPN in the management of this size tumour.