Extended surgical resection for primary retroperitoneal sarcoma. Systematic review and meta- analysis

doi:10.21203/rs.3.rs-1996109/v1

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Systematic Review

Extended surgical resection for primary retroperitoneal sarcoma. Systematic review and meta- analysis

https://doi.org/10.21203/rs.3.rs-1996109/v1

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Background & Objectives: Retroperitoneal sarcomas are often advanced at presentation. Surgery remains the only available curative management. The extent of surgical resection is debatable. There is a strong cause for compartmental resection of the whole hemi-retroperitoneum, but high-level evidence is lacking. This systematic review examines published evidence for the effect of resection policy on the oncologic outcome.

Methods: The PubMed was searched for “retroperitoneal neoplasms”, “surgery”, “surgical procedures, operative”, and “margin of resection”. Web Of Science™ was searched for “retroperitoneal neoplasms” and “surgical management”. English-language articles that investigated retroperitoneal sarcoma in adult patients with extent of surgery as an independent variable and oncologic outcome as endpoints were included.

Results: Twenty-three articles were retained for analysis. All articles were retrospective. Meta-analysis showed equivalence of overall survival with extended surgery versus limited surgery and with sole tumor resection versus en-bloc resection with contiguous organs. Multivisceral resection did not increase morbidity.

Conclusions: The role of universal extended surgery and the subset of patients who may benefit from irradiation treatment remain open questions.

Retroperitoneal

soft tissue sarcoma

compartmental resection

Around 15–20% of soft tissue sarcomas (STS) arise in the retroperitoneum (1, 2). Surgical technique is crucial to the outcome of retroperitoneal sarcomas (RPS). The disease is uncommon, and few surgeons accumulate sufficient experience dealing with it. The proximity of important structures poses considerable risks in many patients. There is paucity of high-level evidence for clinical management (2, 3). Multiple RCTs investigating adjuvant therapy for RPS are ongoing or completed. However, the effect of surgical factors on the outcome is generally based on anecdotal reports. In view of these factors, the authors have undertaken this investigation to examine the impact of the surgical technique on the disease outcome. Specifically, this review examined the published evidence for the effect of resection policy on the oncologic outcome.

1.1 Anatomical Considerations

The space between the posterior parietal peritoneum and the fascia transversalis is the retroperitoneal space. The retroperitoneum is further divided by the embryologic ascent of the kidney carrying a fascial sleeve (4). Thus, three spaces are arranged in the coronal plane with fascial planes in between. These are the anterior pararenal (APR), the perirenal (PR) and the posterior perirenal (PPR) spaces. Retroperitoneal segments of the gut are in the APR space, kidneys ureters and adrenals lie in the PR while the PPR has no visceral content (4–6).

The radiologic boundaries of the three perinephric spaces have been described (7). Of note, the PR space is superiorly continuous with the diaphragm, which often becomes closely related to tumors arising in this space. The perirenal fascia fuse medially with the fascia overlying the great vessels. The line of fascial fusion may be a source of considerable traction force on the great vessels wall during surgical dissection of massive tumors in this space (8).

The perinephric fasciae are normally around 3 mm thick and are easily discernable on cross sectional imaging (6, 9). Pathological conditions further thicken the fascial structures. Several authors have suggested that these fasciae are even multilaminate due to embryonic fusion of mesenteric planes (10–12).

The fascia transversalis contributes to the anterior part of the iliopsoas facia that encloses the psoas major and the iliacus muscles. Although the iliopsoas fascial space is literally outside the retroperitoneal space, STS arising from the iliopsoas almost always expands anteriorly into the retroperitoneal space and are considered retroperitoneal sarcomas. Iliopsoas fascia is usually tough enough to keep these tumors within the corresponding iliopsoas space (1, 3).

1.2. Surgical Considerations

Several publications have established the prognostic importance of achieving a clear margin of resection. A clear microscopic margin (R0 resection) conferred clear survival benefit in multiple hospital (13) and population (14) studies. Similarly, a macroscopic clear margin (R1 resection) is superior to a grossly invaded (R2) margin (15). While the importance pathological margin status as described above is established, the optimal surgical technique to achieve an R0 resection is contested. Enucleation (herein called D1 disssection) implies shelling out the tumor without a discernable gross surgical margin. This procedure is generally inadequate for curative cancer surgery. Carrying the dissection in a healthy tissue plane to ensure a 1 cm cuff of normal tissue improves the chance of achieving a free margin, this surgical strategy may be called D2 dissection. On the other hand, compartmental resection (CR) is a more aggressive surgical strategy (1, 8). In this technique which is labelled D3 dissection for the sake of this review, the whole block of fat and viscera contained in the lateral retroperitoneal compartment is excised en-bloc, reciprocating CR in limb sarcoma surgery. Larger tumors stretch the surrounding organs and make the distinction between D2 and D3 dissections less clear (Fig. 1). Proponents of compartmental resection believe that resection of the whole hemi-retroperitoneum is essential to secure an R0 pathological margin. They cite the lack of a complete fascial envelope in the retroperitoneum and advocate using the surrounding structures as the only available barrier to tumor spread. Opponents of this approach emphasize that viscera resected with RPS are uncommonly infiltrated with the tumor tissue even when grossly adherent to it (16, 17).

In this systematic review, the investigators searched the PubMed and Web of Science™ databases for published evidence to any of the above-mentioned surgical strategies.

2.1. Search Strategy

The National Library of Medicine database (PubMed) was searched Using the Medical Subject Heading (MeSH) thesaurus. Search terms were (“retroperitoneal neoplasms” [major]) AND (“surgical procedures, operative” [major] OR “margin of excision” [major]) OR (“retroperitoneal neoplasms/surgery” [major]).

The Web of Science™ database was searched for terms (“retroperitoneal neoplasms” [topic] AND “surgical management” [topic]).

Search was restricted to English-language articles published in the last 25 years (January 1997 through 2022).

Studies were deemed eligible according to predefined PICO criteria. The review included studies involving adult patients “Participants”, surgical resection with or without visceral / multivisceral resection as an independent variable “Intervention”, primary (non-organ) soft tissue sarcoma of the retroperitoneum “Condition”, and oncologic outcome &/or operative morbidity as “Outcome”.

Search results were screened at the abstract level for relevance. Full-text articles were examined and the articles including the surgical technique as an independent variable and oncologic outcome or operative morbidity as dependent variables were selected.

The retrieved publications were also checked for cited references.

Two investigators independently carried the search and articles were included by consensus. The first author extracted the data. The Pubmed search was first run in September 2021 and was updated in May 2022. Web of Science™ search was conducted in July 2022.

2.2. Quality Scoring

Scoring of the selected articles followed the Methodological Index for Non-Randomized Studies (MINORS) (18). Twelve-point scoring system is used for comparative studies. Each item is scored as 0 (not reported), 1 (reported but inadequate), or 2 (reported and adequate). The maximum score is 24 (table 1).

2.3. Meta-Analysis

Data were extracted into a pre-forma spreadsheet and the effect size measures were retrieved from tables or survival curves according to the method of Tierney et al (19). Meta-analysis was performed with the JASP 0.16.2 software (JASP team, University of Amsterdam). Random effect model was used with log Hazard ratio as the effect size measure. Heterogeneity was measured with I² statistic.

2.4. Protocol registration

The review protocol was prospectively registered in the International prospective register of systematic reviews (PROSPERO) ID = CRD42021277972.

The search flow is depicted in the PRISMA chart (figure 2). Twenty-three articles have been retained for appraisal and analysis. Seven publications compared limited resection to wider resection as a predetermined surgical strategy irrespective of the morbid anatomy of the tumor (table2). More publications compared sole tumor resection to en-bloc resection of the tumor and contiguous organ(s) selectively derived by the tumor relations. Of those, seven articles addressed RPS in general (table 3) and six articles included liposarcomas only (table 4). Three reports included comparison of multivisceral resection to simple resection regarding operative morbidity (table 5). All studies were retrospective.

3.1. Extended Resection

The Instituto Nazionale Tumori group adopted compartmental surgery in 2002. Gronchi and his group (20) published a retrospective single-center series including consecutive patients treated from January 1985 through September 2007. The authors compared patients managed before 2002 to those managed later, assuming that the time when patients received their operation correlated with the type of surgery. The authors republished their analysis a few years later (21) adding patients treated in 2008 to the recent group and adding four more patients to the early period group. Unfortunately, there was no direct information on the surgical procedures in either report, and the comparative groups were not contemporary. These two reports are not included in the meta-analysis.

Bonvalot et al (22) published a retrospective analysis of a French national database. The authors analyzed 374 patients who had been operated for cure. Surgeries were categorized as compartmental or standard. Category assignment was based on patients’ operative reports. The standard surgery group included patients who had selective resection of contiguous organs. Median overall survival was 6 years in the whole cohort. Compartmental resection significantly decreased the risk of abdominal recurrence (HR 3.29 with standard surgery, 95% CI 1.90 to 5.70). The difference persisted in multivariate analysis (HR 1.99, 95% CI 1.03 to 3.84, P value = 0.04). The surgical strategy had no impact on overall survival.

Santos and colleagues (23) conducted a retrospective analysis of 91 consecutive patients treated from 1992 – 2008 at a referral hospital in Brazil. The authors compared compartmental resection to sole tumor resection. Both groups had similar baseline criteria. Overall survival did not differ according to the type of surgery. The authors reanalyzed their cohort including patients who achieved a free pathological margin only (R0 resection). In this subset of patients, sole tumor resection fared better than compartmental surgery in terms of survival and morbidity.

Mussi et al (24) reported the data of 77 primary RPS patients treated from 1997 through 2008 at the Italian Istituto Clinico Humanitas. Simple and multivisceral surgery were associated with comparable overall and disease specific survival (HR 0.989, 95% CI 0.490 to 3.578, P value 0.355) and (HR 0.920, 95% CI 0.205 to 5.323, P value 0.927), respectively.

In response to the debate that ensued, the Trans-Atlantic RPS working group was established (later called the Trans-Atlantic Australasian RPS working group, TARPSWG). The group retrospectively examined 1007 patients treated between 2002 and 2011 at eight high-volume centers. At that time, compartmental surgery was adopted at some sites while limited surgery was the standard at others. Again, the study lacked direct information about surgical procedures. In this report, crude cumulative incidence of local recurrence of well-differentiated liposarcoma at 8 years was best in the centers that had adopted radiation therapy (RT) and compartmental surgery (5% LR, 95% CI 0.7 to 35.5). The corresponding figures for institutions that had not employed routine RT was 34.8% with compartmental surgery, and 42.5% with classic surgery, with overlapping confidence intervals. Local recurrence of leiomyosarcoma was similar in all study siters. Overall survival was similar across all groups (25). The postoperative morbidity outcome of this latter cohort of patients from eight high-volume centers was reported in another article. Overall, the rate of 30-day events was 1 .8% for mortality, 16.4% for serious morbidity, and 10.5% for reoperation. The odds of severe complications increased with four or more resected organs per case (26).

Two publications compared enucleation (D1) to wide margin (D2) resection. A retrospective analysis was conducted for 42 patients treated at the Universita` Cattolica del Sacro Cuore in Italy (27). Of the patients treated for cure, seven had wide resection and 17 had inadequate surgical margin. 5-year disease-free survival was 63.5 ± 21.2 and 28.6 ± 12.6 months, respectively, P value 0.09.

A consecutive series of 56 patients treated at the Universidad Autónoma de Barcelona in Spain included enucleation in 27 patients and en-bloc surgery regardless of infiltration in 29 patients (28). Disease-free survival but not overall survival was better in the radical group.

Table 2 shows the description, quality scoring, and the oncological outcome of the studies that compared extended surgery to less radical surgery.

On meta-analysis, the group effect size “log (HR)” for overall survival was 0.01 (-0.35, 0.35) “mean (95% credible interval)” on Bayesian model and was 0.01 (-0.26, 0.28) on Wald model. I² was 92.8%. The group effect size “log (HR)” for disease-free survival was 0.23 (-0.36, 0.17) “mean (95% credible interval)” on Bayesian model and was 0.25 (-0.16, 0.12) on Wald model. I² was 96.8%.

Figure 3 is a forest plot of overall survival and disease-free survival of the studies that directly compared extended surgery to less radical surgery.

3.2. Selective Organ Resection

A few population-based studies compared simple tumor resection to en-bloc resection of contiguous organs. Weng et al (29) searched SEER database for AJCC stage I RPS operated from 2004 through 2015. The authors reported similar overall and RPS-specific mortality in patients who had simple or en bloc resection. However, en-bloc surgery decreased mortality in a subset of patients who received perioperative RT (HR 0.52, 95%CI 0.30-0.91; P = 0.02).

Villano and colleagues (30) examined the National Cancer Database (NCDB) for stage I-III RPS patients treated in the same period as Weng et al and looking for similar endpoints. Median survival was 84 and 73.9 months in en bloc surgery and simple excision, respectively (P value 0.100). Independently, Littau et al (31) also examined the NCDB for non-lipomatous RPS in almost the same period as above. En-bloc resection, but not preoperative RT, marginally increased the odds of R0 resection in small tumors <5 cm only (HR 7.81, 95% CI 1.23 to 160.51, P value 0.07). On the contrary, in intermediate size and large tumors, en-bloc surgery was associated with increased odds of death (HR 1.42, 95% CI 1.06 to 1.90, P value 0.02) and (HR 1.26, 95% CI 1.03 to 1.54, P value 0.02) respectively. The same group (32) ran a corresponding analysis for liposarcoma (LPS). In this tumor, the type of surgical procedure had no connection with the odds of achieving R0 margin. The odds of death increased in intermediate sized tumors excised en-bloc (HR 1.66, 95% CI 1.04 to 2.65, P value 0.04) and decreased in large tumors that received postoperative RT (HR 0.76, 95% CI 0.64 to 0.90, P value 0.00).

Turner and colleagues (33) examined the Alberta Cancer Registry for RPS patients treated from 1990 through October 2014. Multivisceral resection was performed in 76 patients and simple resection in 26 patients. Patients in the simple excision group received preoperative RT less often but have similar recurrence-free survival to patients in the multivisceral group (HR 0.82, 95% CI 0.42 – 1.60, P value 0.57).

Koeng and colleagues (34) at the University Medical Centre Hamburg-Eppendorf resected any organ that was 1 cm away from the tumor. As such, their multivisceral resection was selectively performed based on the morbid anatomy of every tumor. In their series of 54 consecutive patients, multivisceral resection had no impact on survival compared to single organ resection (median overall survival of 60.3 vs. 53.1 months, respectively. P value 0.63). Hager and colleagues (35) at the University of Freiburg had a similar surgical policy and reached a similar conclusion from the retrospective analysis of a cohort of 46 patients (5-Year Progression-free survival of 65.2% vs. 80.8%. P value 0.267).

On the contrary, a retrospective study of 26 patients from the Japanese Nara Medical University reported a better overall survival associated with resection of adjacent organs (36).

Table 3 outlines the studies investigating contiguous organ resection in RPS.

Other hospital-based studies specifically addressed the impact of resection in liposarcoma. Singer et al (37) examined the records of 177 patients with primary LPS treated at the MSKCC from 1982 through 2001. 38% of patients had contiguous organ resection. In multivariate analysis, contiguous organ resection was associated with the probability of local recurrence (HR 1.7, 95% CI 1.02 to 2.8, P value 0.04) with marginal effect on disease-specific survival (HR 1.9, 95% CI 1.01 to 3.5, P value 0.05).

Ikoma and colleagues (38) from MDACC reported the treatment results of 83 liposarcoma patient. Of the patients treated for cure, 58% had local relapse. Concomitant organ resection was not associated with better DFS (HR 1.022, 95% CI 0.537 to 1.946, P value 0.946). Retrospective hospital studies of Asian populations reached similar conclusions (39, 40) and (Table 4).

Table 4 outlines the studies investigating contiguous organ resection in retroperitoneal liposarcomas.

Because selective organ resection entails en-bloc excision of contiguous organs if, and only if suggested by the operative findings, patients who had this type of surgery probably had more advanced tumors. In this setup, statistical insignificance of the oncological outcome may correspond to clinical benefit. For this reason, we restricted the meta-analysis to studies that demonstrated baseline equivalence of the two groups of patients under comparison. Two propensity score matched studies (29, 30) and two studies with objective evidence of baseline equivalence (36, 38) fulfilled this inclusion criterion for meta-analysis.

On meta-analysis, the group effect size “log (HR)” for overall survival was 0.03 (-0.30, 0.26) “mean (95% credible interval)” on Bayesian model and was 0.02 (-0.17, 0.13) on Wald model. I² was 89.2%.

Figure 4 is the forest plot of overall survival of studies investigating selective organ resection.

3.3. Morbidity of multivisceral resection

The impact of multiple organ resection on postoperative morbidity was also reported. The The American College of Surgeons National Surgical Improvement Program (ACS-NSQIP) database was searched for patients operated on 2005 – 2007 for primary RPS (41). The 30-day rate for mortality was 1.7% and 1% with and without organ resection, respectively. Rate of severe morbidity was 12% and 11%, and the rate of reoperation was 6.9% and 3.1% respectively. Concomitant organ resection did not significantly affect the rates. The same database was independently examined for cases operated from 2012 to 2015. The 30-day rate for mortality was <1% and 2% with and without organ resection, respectively. Rate of severe morbidity was 11% and 8%, and the rate of reoperation was 5% and 3% respectively. Again, no significant difference was observed in association with organ resection (42).

Table 5 outlines the studies demonstrating the impact of multivisceral resection on operative morbidity.

On meta-analysis, the group effect size “log (HR)” for severe morbidity was 0.14 (-0.37, 0.56) “mean (95% credible interval)” on Bayesian model and was 0.18 (-0.22, 0.59) on Wald model. I² was 00.0%.

Figure 5 is the forest plot of severe morbidity of multivisceral resection compared to simple resection.

High level evidence for the optimal surgical policy in retroperitoneal sarcoma is lacking. A landmark National study demonstrated improved abdominal recurrence rates with compartmental resection (22). Later, the TARPSWG published their multicentric study that highlighted two points: first, the improvement in local recurrence rate was restricted to low grade (well-differentiated) liposarcomas. Second, most of the benefit was attributable to adjuvant radiotherapy (25). However, there was no difference in local control after propensity score matching (43). Recently, a large cohort of AJCC stage I RPS, contiguous organ resection was associated with overall survival benefit in the subset of patients who received radiotherapy (29). The EORTC-62092 (STRASS) was a phase III trial that randomized operable RPS to surgery alone or preoperative radiotherapy followed by surgery. No difference in abdominal recurrence free survival was observed. However, subgroup analysis showed benefit in liposarcoma (44). Retrospective analysis of the NCDB pointed to a survival advantage in non-lipomatous RPS that had received radiotherapy (32). In retrospective studies, selection bias may explain the association with better survival, and causal inference cannot be made. Current guidelines discourage the routine use of adjuvant radiotherapy and may consider neoadjuvant irradiation in select cases with high risk of abdominal relapse (3).

The current meta-analysis of all studies that evaluated a universal wide-margin strategy showed equivalence of overall survival and disease-free survival probabilities regardless of surgical policy.

Interpretation of data regarding selective organ resection might even be more misleading. Patients who were offered contiguous organ resection because of tumor adherence generally had more advanced tumors. Statistical insignificance in this situation may suggest clinical benefit in terms of survival. We have restricted the meta-analysis to studies with baseline equivalence of study groups. In the matched cohort, there was clear equivalence of en-bloc resection with sole tumor resection in terms of overall survival.

A meta-analysis is as good as the studies included in it. In the absence of prospective studies, little causal inference can be drawn from a single study or a meta-analysis.

High-level evidence for the best policy for retroperitoneal sarcoma resection is lacking. In general, retrospective studies strongly suggest that overall and disease-specific survival are not affected by the surgical policy. Abdominal recurrence is an important oncological outcome that markedly affect the quality of patients’ life. unfortunately, there is paucity of evidence on this critical outcome, although it would reflect on the disease-free survival figures. Multidisciplinary board discussion and histology-specific treatment plan are essential requirements of optimal retroperitoneal sarcoma management. The role of universal extended surgery remains an open question.

Acknowledgment

The authors are indebted to Prof. Svetlana V. Komarova, Faculty of Dentistry, McGill University, for expert’s support with the methods. JASP is an open-source statistical software sponsored by the University of Amsterdam, among others. URL = https://jasp-stats.org/.

Authors contribution

O.H. conceived the study, planned the research, collected the data, analyzed the data, interpreted the results, and wrote the manuscript. A.S. and S.E. collected the data and discussed the results. All authors agreed on the manuscript.

Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Funding Source

Non existing

Conflict of Interest

The authors have no relevant financial or non-financial interests to disclose.

Ethical statement

Not applicable. No original data was involved in the current research.

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Bonvalot S, Gronchi A, Le Péchoux C, Swallow CJ, Strauss D, Meeus P, et al. Preoperative radiotherapy plus surgery versus surgery alone for patients with primary retroperitoneal sarcoma (EORTC-62092: STRASS): a multicentre, open-label, randomised, phase 3 trial. Lancet Oncol. 2020;21(10):1366–77.
Zhao X, Li P, Huang X, Chen L, Liu N, She Y. Prognostic factors predicting the postoperative survival period following treatment for primary retroperitoneal liposarcoma. Chin Med J (Engl). 2015;128(1):85–90.

Table 1

The Methodological Index for Non-Randomized Studies (MINORS). Adapted from Slim et al (18).
Clearly stated aim
Inclusion of consecutive patients
Prospective collection of data
Endpoint appropriate to the study aim
Unbiased assessment of the endpoints
Follow up period appropriate to the study aim*
Loss of follow up less than 5%
Prospective calculation of the study size
An adequate control group
Contemporary control group
Baseline equivalence of the groups
Adequate statistical analysis

Table 2

Studies that reported the survival outcome of universal extended surgical policy compared to simple excision of RPS
Study	comparison	Total number (Time Period)	Allocation according to	Quality score	Outcome
Malerba 1999 (27)	D2 vs. D1	42 (1984–1995)	operative procedure	15	No difference in DFS, better OS
Bonvalot 2009 (22)	D3 vs. D2	374 (1985–2005)	operative procedure	16	LR better with compartmental surgery, no difference in OS
Santos 2010 (23)	D3 vs. D2	76 (1992–2008)	operative procedure	16	No difference in OS, DFS
Mussi 2011 (24)	D2/3 vs. D1	77 (1996–2008)	Time period	13	No difference in OS, DFS
Gronchi 2012 (21)	D3 vs. D2	331 (1985–2008)	Time period	14	Recently treated patients had better OS, LR and more DM
Gonzalez Lopez 2014 (28)	D2 vs. D1	56 (2000–2010)	operative procedure	16	DFS better with D2 No effect on OS
Gronchi 2016 (25)	D3 vs. D2	1007 (2002–2011)	Institution	12	LR in WDL was better with RT No effect on OS

Table 3

Studies reporting the survival outcome of selective organ resection compared to simple excision of RPS.
Study	Setting	Total number	Period	Quality Score	Outcome
Koenig 2012 (34)	Hospital	54	1994–2006	15	No effect on survival
Hager 2017 (35)	Hospital	46	2001–2014	15	No effect on PFS
Morizawa 2016 (36)	Hospital	23	2002–2014	17	Better OS survival with organ resection
Villano 2020 (30)	Population	3644	2004–2015	17	No difference in median survival, fewer R2 resections
Weng 2021 (29)	Population	886	2004–2015	17	Better OS in patients who received RT and organ resection
Littau 2021 (31)	Population	3394	2004–2016	17	Organ resection associated with R0 resection in RPS < 5 cm, with odds of death in RPS < 5 cm
Turner 2019 (33)	Population	102	1990–2014	18	No effect on RFS

Table 4

Studies reporting the survival outcome of selective organ resection compared to simple excision in liposarcoma patients.
Study	Setting	Total number	Period	Quality Score	Outcome
Singer 2003 (37)	Hospital	177	1982–2001	16	Marginal effect on DSS, increased risk of local recurrence
Ikoma 2017 (38)	Hospital	83	1995–2011	19	No effect on OS, DFS, increased risk of complications
Chen 2021 (39)	Hospital	51	2009–2020	15	No effect on OS or PFS
Lee 2011 (40)	Hospital	21	1990–2005	15	No effect on OS, DFS
Zhao 2015 (45)	Hospital	71	2000–2007	16	No effect on survival
Littau 2021 (32)	Population	4018	2004–2016	17	No effect on R0 resection, increased odds of death in intermediate sized tumors

Table 5

Studies reporting the operative morbidity of multivisceral surgery compared to simple excision of RPS.
*Study*	*Setting*	*Total number*	*Period*	*Quality Score*	*Outcome*
*Tseng 2011 (41)*	Population	156	2005 - 2007	19	Multivisceral resection had no effect on severe morbidity
*McNeill 2018 (26)*	Hospital	1007	2002 - 2011	19
*Judge 2019 (42)*	Population	564	2012 - 2015	19

No competing interests reported.

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Extended surgical resection for primary retroperitoneal sarcoma. Systematic review and meta- analysis

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Background

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3.1. Extended Resection

3.2. Selective Organ Resection

3.3. Morbidity of multivisceral resection

Discussion

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