Recurrent retroperitoneal liposarcoma with multiple surgeries: a case report

Retroperitoneal liposarcoma (RPLPS) is a rare malignant tumor that is typically treated with surgical resection. However, RPLPS often has a high rate of local recurrence, making it crucial to explore new treatment options. In this report, we present the case of a middle-aged woman who experienced seven recurrences and underwent seven surgeries following the initial resection. Currently, the patient's condition remains stable after the eighth surgery. Although there have been numerous reports of RPLPS cases both domestically and internationally, instances of repeated recurrence like this are exceptionally rare. Therefore, we have gathered the patient's case data and conducted a retrospective analysis, incorporating relevant literature, to enhance the understanding of this disease among clinical practitioners.

Short- and long-term post-nephrectomy outcomes for retroperitoneal liposarcoma from a high-volume sarcoma center: a propensity score matching analysis

BACKGROUND

Multivisceral en bloc resection with the ipsilateral kidney is commonly performed in patients with retroperitoneal liposarcoma (RLPS). We evaluated the effect of nephrectomy on short- and long-term outcomes in patients with RLPS.

METHODS

Data from a prospectively maintained database of the Peking University Cancer Hospital Sarcoma Center between April 2011 and August 2022 were analyzed. We classified the RLPS patients who underwent surgery into nephrectomy group (NP) and non-nephrectomy group (non-NP). Patients were matched using a 1:1 propensity score to eliminate baseline differences between groups. Postoperative renal function outcomes, major morbidity, and mortality were analyzed to compare short-term outcomes after nephrectomy. Differences in local recurrence-free survival (LRFS) and overall survival (OS) were compared by Kaplan-Meier analysis with respect to oncological benefits.

RESULTS

In the matched cohort, patients in the NP group had significantly higher postoperative eGFR and CKD stages, but none required dialysis. Patients between NP and non-NP had a comparable major morbidity (p = 0.820) and 60-day mortality (p = 0.475). Patients in the NP group had a higher 5-year LRFS rates than those in the non-NP group (34.5 vs. 17.8%, p = 0.015), and similar 5-year OS rates (52.4 vs. 47.1%, p = 0.401). Nephrectomy was an independent risk factor for LRFS, but not for major morbidity or OS.

CONCLUSIONS

RLPS resection with nephrectomy is related to a mild progression of renal impairment; however, dialysis is rare. En bloc nephrectomy for complete resection of RLPS is safe and improves local control.

Progress in Retroperitoneal Sarcoma Management: Surgical and Radiotherapy Approaches

Surgical resection is the cornerstone of curative treatment for retroperitoneal sarcomas (RPS), aiming for complete excision, yet the complexity of RPS with its proximity to vital structures continues to lead to high local recurrence rates after surgery alone. Thus, the role of radiotherapy (RT) continues to be refined to improve local control, which remains an important goal to prevent RPS recurrence. The recently completed global randomized trial to evaluate the role of surgery with and without preoperative RT - STRASS1, did not demonstrate a significant overall benefit for neoadjuvant RT based on the pre-specified definition of abdominal recurrence-free survival, however, sensitivity analysis using a standard definition of local recurrence and analysis of outcomes by compliance to the RT protocol suggests histology-specific benefit in well- and some de-differentiated liposarcomas. Ultimately, multidisciplinary collaboration and personalized approaches that consider histological sarcoma types and patient-specific factors are imperative for optimizing the therapeutic strategy in the management of RPS.

A systematic review of the role of chemotherapy in retroperitoneal sarcoma by the Australia and New Zealand sarcoma association clinical practice guidelines working party

BACKGROUND

In primary localised resectable retroperitoneal sarcoma (RPS), loco-regional and distant relapse occur frequently despite optimal surgical management. The role of chemotherapy in improving outcomes is unclear.

METHODS

A systematic review was conducted, using the population, intervention, comparison outcome (PICO) model, to evaluate whether neoadjuvant or adjuvant chemotherapy improve outcomes in adults with primary localised resectable RPS. Medline, Embase and Cochrane Central were queried for publications from 1946 to June 2022 that evaluated recurrence free survival, overall survival, and post operative complications. Each study was screened by two independent reviewers for suitability. A qualitative synthesis of the results was performed.

RESULTS

Twenty three studies were identified; one meta-analysis of retrospective studies and 22 retrospective studies including three with propensity matched cohorts. Most studies did not analyse outcomes by histology, detail treatment regimens, provide baseline characteristics or selection criteria for those receiving chemotherapy. Evidence of selection bias was illustrated in several studies. Newcastle-Ottawa quality of retrospective cohort studies was good for 12 studies and poor for 10 studies. All studies were assessed as Level III-2 evidence by the Australian NHMRC hierarchy. Overall, the addition of neoadjuvant or adjuvant chemotherapy to surgery was not associated with improvement in local recurrence, metastasis free survival, disease free survival or overall survival in primary localised resectable RPS. There is some evidence of an association of chemotherapy with worse overall survival. One single centre study showed that neoadjuvant chemotherapy was not associated with increased post operative complications compared to surgery alone in primary localised resectable RPS.

CONCLUSIONS

There is currently no evidence that demonstrates the addition of chemotherapy to surgery improves outcomes in adult patients with primary localised resectable RPS. Available evidence is limited by its retrospective nature and high likelihood of selection bias with chemotherapy generally administered to patients at higher risk of recurrence and many patients not receiving care in high volume sarcoma centres. Randomised trials are required to conclusively determine the role of chemotherapy in primary localised resectable RPS.

Clinical characteristics and management of primary retroperitoneal sarcoma: A literature review

Retroperitoneal sarcoma (RPS) is a rare tumor classified into many histological types. It is also often detected only after it has grown to a considerable size and requires extensive resection of the surrounding organs, making it difficult to offer optimal patient-tailored management. Evidence supporting specific treatment modalities for RPS is insufficient, owing to its rarity. The Japanese clinical practice guidelines for RPS were published in December 2021, with the aim of accumulating existing evidence and indicating the optimal practice for RPS. These guidelines provide important clinical questions (CQs) concerning the diagnosis and treatment of RPS. This review, with a particular focus on primary RPS, attempts to introduce clinical problems in the diagnosis and treatment of RPS and to assess those problems along with the CQs in the guidelines. According to these guidelines, although chemotherapy and radiotherapy are expected to have therapeutic effects, the level of evidence to support these treatments is not very high at present. Accordingly, complete resection of the tumor is the first and only option for managing primary RPS. However, as with other tumors, the demand for multidisciplinary treatment for RPS is increasing. These guidelines will undoubtedly represent a milestone in clinical practice in relation to RPS in the future, and further evidence is expected to be accumulated based on the CQs that have been proposed.

Analysis of recurrence and metastasis patterns and prognosis after complete resection of retroperitoneal liposarcoma

Objective

To analyze the recurrence and metastasis patterns and prognosis after complete resection of retroperitoneal liposarcoma.

Methods

The clinical postoperative follow-up data and results of patients who underwent complete resection of retroperitoneal liposarcoma from September 10, 2014, to September 8, 2021, at Hebei Medical University hospital were collected retrospectively.

Results

A total of 60 patients with complete resection of retroperitoneal liposarcoma, including 33 cases of retroperitoneal liposarcoma recurrence, 2 cases of liver metastasis, and 1 case of lung metastasis, were included. The results showed that 100% of the recurrent sites were located in the primary region of the tumor, with most recurrences located near the kidney, paracolic sulci, and iliac vessels. Three patients had distant metastasis without obvious recurrence on imaging examination. The pathological type of retroperitoneal liposarcoma, Ki67 expression, and presence of serum albumin were risk factors for recurrence and metastasis after complete resection of retroperitoneal liposarcoma. The malignancy and Ki67 expression were independent risk factors for recurrence and metastasis as well as for overall survival of patients undergoing complete resection of retroperitoneal liposarcoma.

Conclusion

Complete resection remains the most effective method to treat retroperitoneal liposarcoma. Patients with pathological types of retroperitoneal liposarcoma showing dedifferentiation, pleomorphism, mixed type, and high Ki67 expression should be closely monitored and observed after complete resection, especially for imaging changes in the primary tumor area.

Retroperitoneal Soft Tissue Sarcoma: Emerging Therapeutic Strategies

Retroperitoneal soft tissue sarcoma (RPS) is a rare and heterogenous disease for which surgery is the cornerstone of treatment. However, the local recurrence rate is much higher than in soft tissue sarcoma of the extremities since wide resection is usually unfeasible in RPS due to its large size, indistinct tumour borders, anatomical constraints and the thinness of the overlying peritoneum. Local recurrence is the leading cause of death for low-grade RPS, whereas high-grade tumours are prone to distant metastases. In recent decades, the role of emerging therapeutic strategies, such as more extended surgery and (neo)adjuvant treatments to improve oncological outcome in primary localised RPS, has been extensively investigated. In this review, the recent data on the evolving multidisciplinary management of primary localised RPS are comprehensively discussed. The heterogeneity of RPS, with their different histological subtypes and biological behaviour, renders a standard therapeutic 'one-size-fits-all' approach inappropriate, and treatment should be modified according to histological type and malignancy grade. There is sufficient evidence that frontline extended surgery with compartmental resection including all ipsilateral retroperitoneal fat and liberal en bloc resection of adjacent organs and structures, even if they are not macroscopically involved, increases local tumour control in low-grade sarcoma and liposarcoma, but not in leiomyosarcoma for which complete macroscopic resection seems sufficient. Additionally, preoperative radiotherapy is not indicated for all RPSs, but seems to be beneficial in well-differentiated liposarcoma and grade I/II dedifferentiated liposarcoma, and probably in solitary fibrous tumour. Whether neoadjuvant chemotherapy is of benefit in high-grade RPS remains unclear from retrospective data and is subject of the ongoing randomised STRASS 2 trial, from which the results are eagerly awaited. Personalised, histology-tailored multimodality treatment is promising and will likely further evolve as our understanding of the molecular and genetic characteristics within RPS improves.

Nomogram development and external validation for predicting overall survival and cancer-specific survival in patients with primary retroperitoneal sarcoma: a retrospective cohort study

BACKGROUND

Primary retroperitoneal sarcoma (RPS) comprises over 70 histologic subtypes, yet there are limited studies that have developed prognostic nomograms for RPS patients to predict overall survival (OS) and cancer-specific survival (CSS). The objective of this study was to construct prognostic nomograms for predicting OS and CSS in RPS patients.

METHODS

We identified a total of 1166 RPS patients from the Surveillance, Epidemiology and End Results (SEER) database, and an additional 261 cases were collected from a tertiary cancer center. The study incorporated various clinicopathological and epidemiologic features as variables, and prediction windows for overall survival (OS) and cancer-specific survival (CSS) were set at 3, 5, and 7 years. Multivariable Cox models were utilized to develop the nomograms, and variable selection was performed using a backward procedure based on the Akaike Information Criterion. To evaluate the performance of the nomograms in terms of calibration and discrimination, we used calibration plots, coherence index, and area under the curve.

FINDINGS

The study included 818 patients in the development cohort, 348 patients in the internal validation cohort, and 261 patients in the external validation cohort. The backward procedure selected the following variables: age, French Federation of Cancer Centers Sarcoma Group (FNCLCC) grade, pre-/postoperative chemotherapy, tumor size, primary site surgery, and tumor multifocality. The validation results demonstrated that the nomograms had good calibration and discrimination, with C-indices of 0.76 for OS and 0.81 for CSS. Calibration plots also showed good consistency between the predicted and actual survival rates. Furthermore, the areas under the time-dependent receiver operating characteristic curves for the 3-, 5-, and 7-year OS (0.84, 0.82, and 0.78, respectively) and CSS (0.88, 0.88, and 0.85, respectively) confirmed the accuracy of the nomograms.

INTERPRETATION

Our study developed accurate nomograms to predict OS and CSS in patients with RPS. These nomograms have important clinical implications and can assist healthcare providers in making informed decisions regarding patient care and treatment options. They may also aid in patient counseling and stratification in clinical trials.

Assessment of inter-centre agreement across multidisciplinary team meetings for patients with retroperitoneal sarcoma

BACKGROUND

Decision-making in the management of patients with retroperitoneal sarcoma is complex and requires input from a number of different specialists. The aim of this study was to evaluate the levels of agreement in terms of resectability, treatment allocation, and organs proposed to be resected across different retroperitoneal sarcoma multidisciplinary team meetings.

METHODS

The CT scans and clinical information of 21 anonymized retroperitoneal sarcoma patients were sent to all of the retroperitoneal sarcoma multidisciplinary team meetings in Great Britain, which were asked to give an opinion about resectability, treatment allocation, and organs proposed to be resected. The main outcome was inter-centre reliability, which was quantified using overall agreement, as well as the chance-corrected Krippendorff's alpha statistic. Based on the latter, the level of agreement was classified as: 'slight' (0.00-0.20), 'fair' (0.21-0.40), 'moderate' (0.41-0.60), 'substantial' (0.61-0.80), or 'near-perfect' (>0.80).

RESULTS

Twenty-one patients were reviewed at 12 retroperitoneal sarcoma multidisciplinary team meetings, giving a total of 252 assessments for analysis. Consistency between centres was only 'slight' to 'fair', with rates of overall agreement and Krippendorff's alpha statistics of 85.4 per cent (211 of 247) and 0.37 (95 per cent c.i. 0.11 to 0.57) for resectability; 80.4 per cent (201 of 250) and 0.39 (95 per cent c.i. 0.33 to 0.45) for treatment allocation; and 53.0 per cent (131 of 247) and 0.20 (95 per cent c.i. 0.17 to 0.23) for the organs proposed to be resected. Depending on the centre that they had attended, 12 of 21 patients could either have been deemed resectable or unresectable, and 10 of 21 could have received either potentially curative or palliative treatment.

CONCLUSIONS

Inter-centre agreement between retroperitoneal sarcoma multidisciplinary team meetings was low. Multidisciplinary team meetings may not provide the same standard of care for patients with retroperitoneal sarcoma across Great Britain.

Primary retroperitoneal sarcoma: A comparison of survival outcomes in specialist and non-specialist sarcoma centres

BACKGROUND

Consensus guidelines outline that patients with primary retroperitoneal sarcoma (RPS) should be managed within specialist sarcoma centres (SSC). There is, however, a paucity of population-based data detailing incidence and outcomes in these patients. Hence, we aimed to evaluate patterns of care among RPS patients in England and compare outcomes for those undergoing surgery in high-volume specialist sarcoma centres (HV-SSC), low-volume SSC (LV-SSC), and non-SSC (N-SSC).

METHODS

Data on patients diagnosed with primary RPS between 2013 and 2018 were extracted from NHS Digital's National Cancer Registration and Analysis Service using the national cancer registration dataset. Diagnostic pathways, treatment, and survival outcomes were compared between HV-SSC, LV-SSC, and N-SSC. Uni- and multivariate analyses were calculated.

RESULTS

Of 1878 patients diagnosed with RPS, 1120 (60%) underwent surgery within 12 months of diagnosis, with 847 (76%) operated on at SSC; of these, 432 patients (51%) were operated on in HV-SSC, and 415 (49%) in LV-SSC. One- and 5-year estimated overall survival (OS) rates for patients undergoing surgery in N-SSC were 70.6% (95% confidence interval [CI]: 64.8-75.7) and 42.0% (CI: 35.9-47.9), compared to 85.0% (CI: 81.1-88.1) and 51.7% (CI: 46.6-56.6) in LV-SSC (p < 0.01), and 87.4% (CI: 83.9-90.2) and 62.8% (CI: 57.9-67.4) in HV-SSC, (p < 0.01). After adjusting for patient- and treatment-related factors, patients treated in HV-SSC were found to have significantly longer OS than those treated at LV-SSC, with an adjusted hazard ratio of 0.78 (CI: 0.62-0.96, p < 0.05).

CONCLUSION

Patients with RPS undergoing surgery in HV-SSC have significantly better survival outcomes than those treated in N-SSC and L-SSC.

Preoperative Radiotherapy in Patients With Primary Retroperitoneal Sarcoma: EORTC-62092 Trial (STRASS) Versus Off-trial (STREXIT) Results

OBJECTIVE

The aim of the present study was to compare the effect of radiotherapy (RT) on abdominal recurrence-free survival (ARFS) in patients with primary retroperitoneal sarcoma treated in the EORTC-STBSG-62092 (STRASS) phase 3 randomized controlled trial (STRASS cohort) and off-trial (STREXIT cohort) and to pool STRASS and STREXIT data to test the hypothesis that RT improves ARFS in patients with liposarcoma.

BACKGROUND

The STRASS trial did not show any difference in ARFS between patients treated with preoperative radiotherapy+surgery (RT+S) versus surgery alone (S).

METHODS

All consecutive adult patients not enrolled in STRASS and underwent curative-intent surgery for a primary retroperitoneal sarcoma with or without preoperative RT between 2012 and 2017 (STRASS recruiting period) among ten STRASS-recruiting centres formed the STREXIT cohort. The effect of RT in STREXIT was explored with a propensity score (PS)-matching analysis. Primary endpoint was ARFS defined as macroscopically incomplete resection or abdominal recurrence or death of any cause, whichever occurred first.

RESULTS

STRASS included 266 patients, STREXIT included 831 patients (727 after excluding patients who received preoperative chemotherapy, 202 after 1:1 PS-matching). The effect of RT on ARFS in STRASS and 1:1 PS-matched STREXIT cohorts, overall and in patients with liposarcoma, was similar. In the pooled cohort analysis, RT administration was associated with better ARFS in patients with liposarcoma [N=321, hazard ratio (HR), 0.61; 95% confidence interval (CI), 0.42-0.89]. In particular, patients with well-differentiated liposarcoma and G1-2 dedifferentiated liposarcoma (G1-2 DDLPS, n=266) treated with RT+S had better ARFS (HR, 0.63; 95% CI, 0.40-0.97) while patients with G3 DDLPS and leiomyosarcoma had not. At the current follow-up, there was no association between RT and overall survival or distant metastases-free survival.

CONCLUSIONS

In this study, preoperative RT was associated with better ARFS in patients with primary well-differentiated liposarcoma and G1-2 DDLPS.

Significant Predictors of Postoperative Morbidity After Radical Resection of Retroperitoneal Sarcoma in a Tertiary Center

BACKGROUND

The safety of multivisceral resection of retroperitoneal sarcoma is an issue. Previous reports have investigated its associations with the pattern of resection and factors recognized mostly per operatively.

METHODS

All consecutive RPS resections from May 2015 to April 2022 were studied retrospectively with respect to adverse events. Two univariate and multivariate logistic regression analyses were performed to investigate the associations between severe adverse events and factors recognized pre- and per operatively. Associations of adverse events with overall survival (OS) and local recurrence (LR) were investigated.

RESULTS

A total of 265 surgical interventions corresponding to 251 patients were recorded (38 RPS surgeries/year). Severe postoperative adverse events (Clavien-Dindo ≥ 3) occurred in 50 patients (18.9%), 15 (5.6%) patients underwent an iterative laparotomy, and 6 patients (2.3%) died within 90 days. On multivariate analysis including all parameters known preoperatively, male sex, performance status, dedifferentiated liposarcoma histology, and low serum albumin level were found to be significant predictors of major complications, whereas the timing of surgery and preoperative treatment were not. On univariate analysis including all per operative parameters, transfusion requirement, operative time, number of digestive anastomoses, and pancreas and/or major arterial resection were found to entail higher operative risk. On multivariate analysis, only transfusion requirement was significant. There was no impact of postoperative adverse events on OS or LR.

CONCLUSIONS

The recognition of preoperative parameters that impact safety could mitigate the extent of the surgery, specifically the resection of adherent organs not overtly invaded. For the best decision, this surgery should be performed in referral centers.

Organ Infiltration and Patient Risk After Multivisceral Surgery for Primary Retroperitoneal Liposarcomas

BACKGROUND

The extent of histological organ involvement (HOI) to organs and structures of a retroperitoneal liposarcoma may have prognostic implications. This study investigated incidence, characteristics, and risk association of HOI in these patients.

PATIENTS AND METHODS

Data of patients who underwent multivisceral resection for primary liposarcoma (2009-2014) were retrospectively analyzed. HOI was the variable of interest and was classified into four degrees: absent (HOI-0), perivisceral (HOI-1), initial (HOI-2), and advanced (HOI-3). Primary endpoint was overall survival (OS). Secondary endpoint was disease-free survival (DFS). The prognostic value of HOI was adjusted for preoperative treatment and the Sarculator nomogram score.

RESULTS

A total of 109 patients were included. HOI-0, HOI-1, HOI-2, and HOI-3 were detected in 9 (8.3%), 11 (10.1%), 43 (39.4%), and 46 (42.2%) patients. Median follow-up was 8.4 years [interquartile range (IQR) 7.2-9.6 years]. There were 68 recurrences and 50 patient deaths observed, resulting in a 10-year OS and DFS of 51.1% [95% confidence interval (CI) 41.9-62.1%] and 34.1% (95% CI 25.2-46.1%), respectively. Clinically relevant HOIs (HOI-2 and HOI-3) were found in 35/45 (77.8%) and 54/64 (84.4%) cases of well- and de-differentiated liposarcomas, respectively. On multivariable survival analysis, patients with HOI-3 had significantly shorter OS (HOI-3 vs HOI-0/HOI-1 HR 2.92; p = 0.012) and DFS (HOI-3 vs HOI-0/HOI-1 HR 2.23; p = 0.045), independently of the nomogram score (OS: HR 2.93; p < 0.001; DFS: HR 1.78; p = 0.003).

CONCLUSIONS

Initial and advanced HOIs are frequently detected in both well-differentiated and de-differentiated liposarcomas, supporting that multivisceral resection may be needed. HOI stratifies the risk of patients with primary retroperitoneal liposarcoma.

Survival analysis and prognostic factors of retroperitoneal liposarcoma curative surgery in a single centre. Analysis of adjacent organ invasion between imaging and definitive histopathology

INTRODUCTION

Retroperitoneal liposarcoma (RPL) is a rare primary mesenchymal tumour that develops in retroperitoneal adipose tissue. Unlike the majority of published series, this homogeneous cohort focuses on RPL. The main purpose of this study is to evaluate the overall and recurrence-free survival of RPLs who underwent excision surgery and the prognostic factors involved.

PATIENTS AND METHODS

A total of 82 patients from a single centre, who underwent curative surgery for histologically confirmed retroperitoneal liposarcoma between 2008 and 2020, were analysed in the study. Compartmental surgical excision was advised as per the guidelines. The primary endpoints were 5 years of overall survival and recurrence-free survival. Predictable tumour invasion of adjacent organs, based on a pre-operative CT scan, was also investigated to test the correlation between pre-operative imaging and pathological data.

RESULTS

Median follow-up was 61.6 months. Five year overall survival was 71.9% [95% CI: 59.8; 80.9] and 5 year recurrence-free survival was 49% [95% CI: 36.4; 60.5]. Following multivariable analysis, the factors influencing overall survival were tumour rupture and onset of severe complications (Dindo-Clavien grade ≥3). Factors influencing recurrence-free survival were neoadjuvant radiotherapy and tumour rupture. A significant correlation (p < 0.05) was found between predicted invasion based on a CT scan of the colon, spleen, adrenal gland, posterior abdominal wall and diaphragm, and pathological invasion.

CONCLUSIONS

Curative compartmental surgery remains the gold standard treatment for RPL. This study, highlights the fact that the quality of the surgical excision is a crucial factor in patient prognosis.

Histology-tailored multidisciplinary management of primary retroperitoneal sarcomas

Until recently, the recommendation for primary retroperitoneal sarcomas (RPS) was to perform a complete en-bloc gross excision, (neo) adjuvant treatments being options which were not validated by randomized studies, with a large discrepancy of use between centers. The heterogeneity of RPS, with their different biological behaviour, renders a homogenous therapeutic and surgical approach probably inappropriate. Recent studies, both surgical and dedicated to adjuvant treatments, allow refining these recommendations. This review summarizes recent advances and directions.

Management of recurrent retroperitoneal sarcomas

Recurrent retroperitoneal sarcomas are rare, with patterns of recurrence determined by the histologic subtype. A range of patient characteristics and treatment profiles combined with a myriad of presentations and clinical courses of recurrences make this diverse entity challenging to manage. Although surgical resection improves survival in select patients, the oncological outcomes are inferior to that of primary retroperitoneal sarcomas. Management options for unresectable disease include local ablative therapy, radiation and systemic therapy, with palliative surgery indicated occasionally. Attempts at disease control must be balanced with potential morbidity and impact on the patient's quality of life. This review aims to offer insights into the current understanding of recurrent retroperitoneal sarcomas and provide some guidance on management.

How to treat liposarcomas located in retroperitoneum

Almost half of retroperitoneal (RP) sarcomas are liposarcomas (LPS). The large majority of RP LPS are either well-differentiated LPS (WDLPS) or dedifferentiated LPS (DDLPS), these latter further classified according to grading in G2 and G3 DDLPS. Surgery is the only potentially curative treatment to achieve local control and possibly cure in primary localized disease. Over the last decade, a better delineation of the different histology-specific patterns of failure and the development of nomograms predictors of outcome has led to a better management of these rare tumors, with a special focus on non-surgical treatments. Available evidences - although far from exhaustive - show that radiation therapy might have a role, if any, as neoadjuvant treatment in locally aggressive histologies (i.e. WDLPS and G2 DDLPS), while it does not seem beneficial for histologies with a higher metastatic risk (i.e. G3 DDLPS and leiomyosarcoma). Neoadjuvant chemotherapy, instead, can be considered to reduce the risk of distant metastasis while waiting for the results of an ongoing RCT (STRASS-2) evaluating its effect in these tumors. However, given the rarity of these diseases and the subsequent lack of strong evidences to guide treatment, outcome improvement in these patients remains a challenge. Patients' referral to a sarcoma center where a dedicated specialized multidisciplinary team tailor optimal treatment on a case-by-case basis is crucial to ensure these patients the best outcome. Refining available nomograms - e.g including molecular variables - and identifying predictors of response/toxicity to chemotherapy and immunotherapy might be significantly helpful in tailoring treatments to the patient's characteristics. Also, new systemic agents are eagerly awaited for improving the management further.

Preoperative Dose-Escalated Intensity-Modulated Radiotherapy (IMRT) and Intraoperative Radiation Therapy (IORT) in Patients with Retroperitoneal Soft-Tissue Sarcoma: Final Results of a Clinical Phase I/II Trial

BACKGROUND

To report the final results of a prospective, one-armed, single-center phase I/II trial (NCT01566123).

METHODS

Between 2007 and 2017, 37 patients with primary or recurrent (N = 6) retroperitoneal sarcomas were enrolled. Treatment included preoperative IMRT of 45-50 Gy with a simultaneous integrated boost of 50-56 Gy, surgery and IORT. The primary endpoint was local control (LC) at 5 years. The most common histology was dedifferentiated liposarcoma (51%), followed by leiomyosarcoma (24%) and well-differentiated liposarcoma (14%). The majority of lesions were high-grade (FNCLCC G1: 30%, G2: 38%, G3: 27%, two missing). Five patients were excluded from LC analysis per protocol.

RESULTS

The minimum follow-up of the survivors was 62 months (median: 109; maximum 162). IORT was performed for 27 patients. Thirty-five patients underwent gross total resection; the pathological resection margin was mostly R+ (80%) and, less often, R0 (20%). We observed 10 local recurrences. The 5-year LC of the whole cohort was 59.6%. Eleven patients received a dose > 50 Gy plus IORT boost; LC was 64.8%; the difference, however, was not significant (p = 0.588). Of 37 patients, 15 were alive and 22 deceased at the time of final analysis. The 5-year OS was 59.5% (68.8% per protocol).

CONCLUSIONS

The primary endpoint of a 5-year LC of 70% was not met. This might be explained by the inclusion of recurrent disease and the high rate of G3 lesions and leiomyosarcoma, which have been shown to profit less from radiotherapy. Stratification by grading and histology should be considered for future studies.

Surgical Management of Retroperitoneal Sarcoma

Surgery is the cornerstone of treatment for retroperitoneal sarcoma (RPS). Surgery should be performed by a surgical oncologist with sub-specialization in this disease and in the context of a multidisciplinary team of sarcoma specialists. For primary RPS, the goal of surgery is to achieve the complete en bloc resection of the tumor along with involved organs and structures to maximize the clearance of the disease. The extent of resection also needs to consider the risk of complications. Unfortunately, the overarching challenge in primary RPS treatment is that even with optimal surgery, tumor recurrence occurs frequently. The pattern of recurrence after surgery (e.g., local versus distant) is strongly associated with the specific histologic type of RPS. Radiation and systemic therapy may improve outcomes in RPS and there is emerging data studying the benefit of non-surgical treatments in primary disease. Topics in need of further investigation include criteria for unresectability and management of locally recurrent disease. Moving forward, global collaboration among RPS specialists will be key for continuing to advance our understanding of this disease and find more effective treatments.

Recurrent metastatic retroperitoneal dedifferentiated liposarcoma: a case report and literature review

BACKGROUND

Retroperitoneal liposarcoma (RPLPS), a rare tumor, is often treated using surgical procedures as the first choice for treatment. However, there is no consensus on the scope of surgical resection. In addition, the treatment outcomes of conventional radiotherapy and chemotherapy have not been satisfactory, particularly for specific types of LPS, such as dedifferentiated LPS. In this case study, we present a brief review of other cases of RPLPS, highlighting the selection of surgical scope for RPLPS and related adjuvant treatment for advanced RPLPS.

CASE PRESENTATION

A case study is reported regarding an extremely rare recurrent and metastatic retroperitoneal dedifferentiated LPS. The primary RPLPS tumor, with a diameter of 20 cm and a weight of 2.5 kg, occupied the whole left abdomen and adhered to the left kidney. A surgical tumor resection combined with a left nephrectomy is performed. During the 6th -month postoperative follow-up examination, we observed the local recurrence of the tumor in the operation area, in addition to multiple metastatic tumors in both lungs. Further, the prescribed 3-month targeted treatment with anlotinib significantly reduced the size of the metastatic pulmonary tumors. However, the recurrent retroperitoneal tumors showed no significant change in size. Eventually, we observed no substantial evidence of tumor progression, with the patient's condition under control.

CONCLUSION

The case demonstrated that the postoperative recurrence of widespread RPLPS required R0 resection to cure the disease, considering targeted therapy for advanced RPLPS control.

IOeRT in retroperitoneal sarcoma: Towards more organ preservation with comparable oncological outcomes

BACKGROUND

Retroperitoneal sarcomas (RPS) present a surgical challenge with high rates of local recurrence (LR). We investigated the role of intraoperative electron radiotherapy (IOeRT) in reducing LR after surgical resection of RPS.

METHODS

A retrospective analysis of all patients who underwent surgical resection for RPS between 2014 and 2021 at a tertiary academic referral center (n = 172). Patients included underwent surgical resection of their RPS and received IOeRT (n = 36) and were compared by case control matching to patients with similar tumor characteristics (recurrence status and tumor grade) that did not receive IOeRT (n = 36).

RESULTS

The median length of hospitalization was 8 days (range, 4-34) in the IOeRT group and 10 days (range, 2-42) in the non-IOeRT group (p = 0.25). The mean operating room (OR) time was 4h (±1.3) and 4h (±1.9) in the IOeRT and non-IOeRT groups respectively, (p = 0.37). Complete resection with R0 margins was achieved in 30 patients (83.3%) and 24 patients (66.6%) in the IOeRT and non-IOeRT groups, respectively (p = 0.1). R1 resection was achieved in 6 patients (16.6%) and 12 patients (33.3%) respectively, (p = 0.1). The resected organ weighted score was significantly different between the groups; score 0 observed in 19 (52.7%) patients in the IOeRT group and 3 (8.3%) in the non-IOeRT group (p < 0.001), score 1 observed in 7 (19.4%) in the IOeRT group and 17 (47.2%) in the non-IOeRT group (p = 0.012). The rate of severe complications (CD score>3) did not differ between the groups, 5 (13.8%) patients in the IOeRT group and 9 (25%) patients in the non-IOeRT group (p = 0.23). No radiation associated complications were noted. The 2-year local recurrence free survival (LRFS) was 75.9% in the IOeRT group and 60.3% in the non-IOeRT group (p = 0.4). The 2-year IOeRT field recurrent free survival (IRFS) was 88.4% in the IOeRT group and 60.3% in the non-IOeRT group (p = 0.04).

CONCLUSIONS

The use of IOeRT did not increase the rate of surgical complications and was associated with superior local control in the radiation field, improved organ preservation without an impact on overall survival.

Management of Recurrent Retroperitoneal Sarcoma

Recurrence after resection of retroperitoneal sarcoma is common and varies by histological subtype. Pattern of recurrence is similarly affected by histology (e.g., well-differentiated liposarcoma is more likely to recur locoregionally, whereas leiomyosarcoma is more likely to develop distant metastases). Radiotherapy may provide effective locoregional control in limited circumstances and the data on the impact of chemotherapy are scant. Surgery for locally recurrent disease is associated with the greatest survival benefit; however, data are retrospective and from a highly selected subgroup of patients. Limited retrospective data have also suggested a survival association with the resection of limited distant metastases. Given the complexity of these patients, multidisciplinary evaluation at a high-volume sarcoma center is critical.

Giant retroperitoneal liposarcoma measuring 27 × 29 × 36 cm: a case report

Retroperitoneal tumors are rare neoplasms that can reach great dimensions due to a slow growth pattern. Although these tumors rarely metastasize, they have a great risk of recurrence, and majority of times these lesions are a challenge for the surgeon. We report the case of a 63-year-old woman who presented with symptoms of large bowel obstruction and was diagnosed with a large heterogenous mass located in the retroperitoneal space. The fine needle biopsy revealed the histology of liposarcoma. The purpose of this article is to report our approach in management of this kind of tumor. Tumor size (27.1 × 29.1 × 36.1 cm) and involvement to the adjacent organs was a challenge for us in order to reach safe oncological margins. In these cases, the risk of recurrence is high; therefore, the patient should be screened at 6, 12 and 24 months post procedure. Chemotherapy or radiotherapy for this tumor is not yet defined, and if operable, surgery is the treatment of choice.

Management of pelvic sarcoma

Pelvic sarcomas are a rare and heterogenous group of tumors divided into two groups: soft tissue sarcomas and bone sarcomas. Soft tissue sarcomas of the pelvis include most commonly liposarcoma, leiomyosarcoma, gastrointestinal stromal tumors, malignant peripheral nerve sheath tumors, and solitary fibrous tumors. Bone sarcomas of the pelvis most commonly include osteosarcoma and chondrosarcoma. Multidisciplinary treatment at a center experienced in the treatment of sarcoma is essential. Management is dictated by histologic type and grade. Surgical resection with wide margins is the cornerstone of treatment for pelvic sarcomas, although this is often challenging due to anatomic constraints of the pelvis. Multimodal treatment is critical due to the high risk of local recurrence in the pelvis.

Patients with first recurrent retroperitoneal sarcoma that can be macroscopically completely resected can achieve comparable outcomes with that of primary patients after en bloc resection of tumor and adjacent organs

The outcomes of patients with primary retroperitoneal sarcoma (RPS) are significantly superior to those with recurrence. En bloc resection of tumor and adjacent organs is recommended in primary RPS. However, whether en bloc resection of tumor and adjacent organs can benefit recurrent patients or some recurrent patients is unclear. We compared the outcomes of patients with primary RPS, first recurrence (RPS-Rec1), and ≥2 recurrences (≥RPS-Rec2) to evaluate the value and criteria for en bloc resection of tumor and adjacent organs in recurrent cases. We evaluated the safety of en bloc resection of tumor and adjacent organs by assessing operation time, blood loss volume, postoperative morbidities (POM), and efficacy by comparing local recurrence and peritoneal metastasis (LR-PM), distant metastasis, progression-free survival (PFS), and overall survival (OS). A total of 101, 47, and 30 patients with primary RPS, RPS-Rec1, and ≥RPS-Rec2 were included, respectively. Recurrent RPS invaded more adjacent organs and surrounding fat tissue than primary RPS. The operation time, amount of blood loss, incidence of grade III–V POM, LR-PM rate, PFS, and OS in the RPS-Rec1 group were similar to those of the primary group, both of which were significantly superior to those of the ≥RPS-Rec2 group. Macroscopically incomplete resection and high-grade RPS rather than first recurrence were independent risk factors for LR-PM, PFS, and OS. In conclusion, the safety and efficacy of en bloc resection of tumor and adjacent organs in RPS-Rec1 were comparable with those in primary RPS but significantly superior to those of ≥RPS-Rec2. For RPS-Rec1, comparable outcomes to patients with primary RPS can be achieved, particularly in those in whom a macroscopically complete resection is achieved.

Retroperitoneal Sarcomas: a Current Review on Management

Retroperitoneal sarcomas are heterogeneous tumours with variable disease biology and outcomes. The prognosis is primarily related to tumour histology and grade as well as the ability to achieve margin negative resection. Surgery involves compartment or contiguous organ resection to achieve the above goal. Careful utilization of neoadjuvant and adjuvant strategies like radiotherapy and/or chemotherapy can lead to improvement in margin status, thereby contributing to better local control and possibly reducing systemic dissemination. Use of targeted therapies has paved newer pathways of treatment integration centred on molecular and genetic targets. The aim of this review is to update the reader on all aspects of retroperitoneal sarcoma management including emphasis on pertinent and landmark trials in this regard.

A systematic review of margin status in retroperitoneal liposarcomas: Does the R0 margin matter?

Retroperitoneal liposarcomas (RPLPSs) are a rare tumor group for which current guidelines recommend aggressive en bloc resection to attain microscopically negative (R0) margins. To ensure R0 margins, resection of adherent or adjacent organs is often required. However, it is still unclear if R0 margins confer any additional benefit to patients over a grossly negative but microscopically positive (R1) margin. We performed a systematic search of PubMed and Embase databases for studies including patients receiving R0 or R1 resection for RPLPS. Nine retrospective cohort studies, one prospective cohort study, and 49 case reports/case series were included. A total of 552 patients with RPLPS were evaluated: 346 underwent R0 resection and 206 underwent R1 resection. In the R0 group, 5-year overall survival (OS) ranged from 58.3% to 85.7%; local recurrence (LR) ranged from 45.5% to 52.3%. In the R1 group, 5-year OS ranged from 35% to 55.3%; LR ranged from 66.7% to 91.7%. Among cohort studies, OS, disease-free survival (DFS), LR rate, and LR-free survival (LRFS) were significantly associated with R0 resections. Assessment of case series and reports suggested that the R0 margin led to a slightly higher morbidity than that of R1. In conclusion, this review found the R0 margin to be associated with reductions in LR rates and improved OS when compared with the R1 margins, though accompanied by slight increases in morbidity. The roles of tumor histotype and perioperative chemotherapy or radiotherapy were not well-elucidated in this review.

Retroperitoneal Sarcomas: Histology Is Everything

Retroperitoneal sarcomas (RPS) are a rare subset of soft tissue sarcoma that are composed of only a few histologic subtypes, each with a distinct tumor biology, clinical presentation, preferred treatment strategy, recurrence risk, and surveillance plan. In the modern era of precision medicine, our understanding of the implications of subtype tumor biology and anatomic location has led to a more nuanced, histology-specific approach to therapy, including surgery, neoadjuvant radiation therapy, and/or chemotherapy. This article provides a summary of recent updates to the management of RPS.

Lipoma and Its Doppelganger: The Atypical Lipomatous Tumor/Well-Differentiated Liposarcoma

Lipomatous tumors are among the most common soft tissue lesions encountered by the general surgeon. Shared history and clinical presentation make differentiation between benign lipomas and low-grade liposarcomas a diagnostic dilemma. This article reviews the epidemiology, clinical history, diagnostic workup, management, natural history, and surveillance of benign lipomas and atypical lipomatous tumors/well-differentiated liposarcomas. Although it is important that aggressive, potentially malignant atypical lipomatous tumors and liposarcomas be managed in a multidisciplinary, preferably high-volume setting, it is equally as important for the nonspecialist general surgeon to be familiar with lipoma and its doppelganger-the well-differentiated liposarcoma.

A novel nomogram model to predict the overall survival of patients with retroperitoneal leiomyosarcoma: a large cohort retrospective study

Retroperitoneal leiomyosarcomas (RLS) are the second most common type of retroperitoneal sarcoma and one of the most aggressive tumours. The lack of early warning signs and delay in regular checkups lead to a poor prognosis. This study aims to create a nomogram to predict RLS patients' overall survival (OS). Patients diagnosed with RLS in the Surveillance, Epidemiology, and End Results (SEER) database between 2000 and 2018 were enrolled in this study. First, univariable and multivariable Cox regression analyses were used to identify independent prognostic factors, followed by constructing a nomogram to predict patients' OS at 1, 3, and 5 years. Secondly, the nomogram's distinguishability and prediction accuracy were assessed using receiver operating characteristic (ROC) and calibration curves. Finally, the decision curve analysis (DCA) investigated the nomogram's clinical utility. The study included 305 RLS patients, and they were divided into two groups at random: a training set (216) and a validation set (89). The training set's multivariable Cox regression analysis revealed that surgery, tumour size, tumour grade, and tumour stage were independent prognostic factors. ROC curves demonstrated that the nomogram had a high degree of distinguishability. In the training set, area under the curve (AUC) values for 1, 3, and 5 years were 0.800, 0.806, and 0.788, respectively, while in the validation set, AUC values for 1, 3, and 5 years were 0.738, 0.780, and 0.832, respectively. As evidenced by the calibration curve, the nomogram had high prediction accuracy. Moreover, DCA revealed that the nomogram had high clinical utility. Furthermore, the risk stratification system based on the nomogram could effectively categorise patients into three mortality risk subgroups. Therefore, the developed nomogram and risk stratification system may aid in optimising the treatment decisions of RLS patients to improve treatment prognosis and maximise their healthcare outcomes.

Treatment for local control of retroperitoneal and pelvis sarcomas: A review of the literature

Retroperitoneal and pelvis sarcomas are uncommon tumors for which complete surgical resection is the mainstay of treatment. However, achieving complete gross resection with microscopically negative margins is challenging, and local recurrence rates can be high. Patients often succumb to uncontrolled local disease. Radiation therapy offers a potential means for sterilizing microscopic residual disease, although its use continues to be controversial. Chemotherapy alone or in combination with radiation continues to be investigated as an adjunct to surgery, along with immunotherapy and targeted therapies. In this review, we discuss the current management of retroperitoneal and pelvis sarcomas, focusing on studies of surgery and radiation therapy to maximize local control.

First and further-line multidisciplinary treatment of retroperitoneal sarcomas

PURPOSE OF REVIEW

To review current knowledge and recent advances in retroperitoneal sarcoma management.

RECENT FINDINGS

Surgery, radiotherapy, and medical treatments of retroperitoneal sarcomas should take into account the peculiarities of each histotype and the unique anatomical site. Surgery remains the mainstay of treatment and the only chance of cure for these diseases. In low-grade retroperitoneal sarcomas, like well differentiated liposarcoma, where the leading cause of death is dominated by local rather than distant relapses, treatment of the primary tumor encompasses extended surgery with multiorgan resection and evaluation of preoperative radiotherapy. Conversely, surgery is usually more conservative and without radiotherapy in those retroperitoneal sarcomas, such as leiomyosarcoma, characterized by a high risk of metastatic spread that prompted also the evaluation of neoadjuvant, histotype-driven chemotherapy. Surgery might have a role also for relapsed disease, despite long-term disease control probability declines at each recurrence. In advanced stages, anthracyclines still retain a key role and all medical treatment strategies should follow the specific chemosensitivity of each histotype to improve patient's outcomes.

SUMMARY

The rarity and heterogeneity in biological behavior and clinical presentation of retroperitoneal sarcomas deserves a multidisciplinary and histotype-driven treatment at all stages of the disease to be performed in highly specialized centers.

Retroperitoneal and Mesenteric Liposarcomas

Retroperitoneal liposarcomas are a rare entity and are comprised mostly of the well-differentiated and dedifferentiated subtypes. Eight-year survival ranges from 30% to 80% depending on histologic subtype and grade. Surgery is the cornerstone of treatment and compartment resection is the current standard. Mesenteric liposarcomas are extremely rare and comprise more high-grade lesions, with poorer prognosis of 50% 5-year overall survival. They are managed with a similar aggressive surgical approach. This review presents the current management of retroperitoneal and mesenteric liposarcomas.

Adjuvant therapy for retroperitoneal sarcoma: a meta-analysis

Background

Adjuvant therapy is a promising treatment to improve the prognosis of cancer patients, however, the evidence base driving recommendations for adjuvant radiotherapy (ART) or chemotherapy (ACT) in retroperitoneal sarcomas (RPS) primarily hinges on observational data. The aim of this study was to evaluate the effectiveness of adjuvant therapy in the management of RPS patients.

Methods

We searched PubMed, Web of Science, Embase, ASCO Abstracts, and Cochrane Library for comparative studies (until December 2020) of adjuvant therapy versus surgery alone. Data on the following endpoints were evaluated: overall survival (OS), local recurrence (LR), recurrence-free survival (RFS), and metastasis-free survival (MFS). Data were summarized as hazard ratios (HR) with 95% confidence intervals (CI). Risk of bias of studies was assessed with Begg’s and Egger’s tests.

Results

A total of 15 trials were eligible, including 9281 adjuvant therapy and 21,583 surgery alone cases (20 studies for OS, six studies for RFS, two studies for LR, and two studies for MFS). Meta-analysis showed that ART was associated with distinct advantages as compared to surgery alone, including a longer OS (HR = 0.80, P < 0.0001), a longer RFS (HR = 0.61, P = 0.0002), and a lower LR (HR = 0.31, P = 0.005). However, this meta-analysis failed to demonstrate a benefit of ACT for RPS patients, including OS (HR = 1.11, P = 0.19), RFS (HR = 1.30, P = 0.09) and MFS (HR = 0.69, P = 0.09). In the sensitivity analysis, ACT was associated with a worse OS (HR = 1.19, P = 0.0002). No evidence of publication bias was observed.

Conclusions

Overall, the quality of the evidence was moderate for most outcomes. The evidence supports that ART achieved a generally better outcome as compared to surgery alone.

Supplementary information

The online version contains supplementary material available at 10.1186/s13014-021-01774-w.

18F-Fluorodeoxyglucose Positron Emission Tomography Is Useful in the Evaluation of Prognosis in Retroperitoneal Sarcoma

Simple Summary

Retroperitoneal sarcomas are difficult malignancies to treat because complete surgical resection is the only effective treatment option, but it is difficult to secure sufficient surgical margins. It is essential for developing a treatment strategy to assess tumor aggressiveness and predict prognosis for patients. However, the aggressiveness of retroperitoneal sarcomas before treatment cannot be fully evaluated. In patients with resectable soft tissue sarcomas or several carcinomas, SUV evaluated with FDG-PET has been reported to be a valuable prognostic parameter. However, the correlation between SUVmax on FDG-PET and the prognosis of several histological subtypes in retroperitoneal sarcoma, including dedifferentiated liposarcoma, well-differentiated liposarcoma, and leiomyosarcoma, remains uncertain. This study revealed that SUVmax calculated with FDG-PET was useful as a prognostic factor in retroperitoneal sarcoma, especially in dedifferentiated liposarcoma and Grade2 retroperitoneal sarcoma.

Abstract

Background: Retroperitoneal sarcomas are rare neoplasms that occur in the retroperitoneum. Complete surgical resection is the only effective treatment option. The prediction of prognosis by histological diagnosis has not yet been established. The purpose of this study was to identify the usefulness of [18-F] fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging for validating the prognosis of retroperitoneal sarcoma (RPS) established by histological diagnosis. Methods: We retrospectively reviewed 201 patients with RPS treated at the Osaka International Cancer Institute between 2010 and 2021. We extracted the clinical data, including standardized uptake values (SUVs), evaluated with FDG-PET, and statistically analyzed the data. Results: The median age of patients was 64 years (range, 31–85 years). A total of 101 (50.2%) patients were men, and 100 (49.8%) were women. Surgical resection was performed in 155 (77.1%) patients. On histological analysis, 75 (37.3%), 52 (25.9%), and 29 (14.4%) patients were diagnosed with dedifferentiated liposarcoma, well-differentiated liposarcoma, and leiomyosarcoma, respectively. The median survival time for patients with high maximum SUV (SUVmax) (≥4) or low SUVmax (<4) was 275.8 months and 79.5 months, respectively. Furthermore, among the patients with dedifferentiated liposarcoma, the overall survival rate for patients with high SUVmax (≥4) was significantly lower than that of those with low SUVmax (<4). Conclusions: The present study demonstrated that SUVmax calculated with FDG-PET was useful as a prognostic factor in RPS, especially in dedifferentiated liposarcoma and Grade2 RPS. To devise a treatment strategy for RPS, SUVmax during FDG-PET scan may be considered for clinical assessment.

Postoperative Outcome of Surgery with Pancreatic Resection for Retroperitoneal Soft Tissue Sarcoma: Results of a Retrospective Bicentric Analysis on 50 Consecutive Patients

BACKGROUNDS

Multivisceral resection is the standard treatment for retroperitoneal sarcoma (RPS) during which pancreas resection may be necessary.

METHODS

All consecutive patients operated for RPS with pancreatectomy in 2 expert centers between 1993 and 2018 were retrospectively analyzed.

RESULTS

Fifty patients (median age: 57 years, IQR: [46-65]) with a primary (n = 33) or recurrent (n = 17) RPS underwent surgery requiring pancreas resection (distal pancreatectomy (DP) (n = 43), pancreaticoduodenectomy (PD) (n = 5), central pancreatectomy (n = 1), and atypical resection (n = 1)). Severe postoperative morbidity (Clavien-Dindo III-IV) was observed in 14 patients (28%), and 7 of them (14%) required reoperation for anastomotic bowel leakage (n = 5), gastric volvulus (n = 1), or hemorrhage (n = 1). Pancreas-related complications occurred in 25 patients (50%): 10 postoperative pancreatic fistulas (POPF) (grade A (n = 12), grade B (n = 6), grade C (n = 1)), 13 delayed gastric emptying (grade A (n = 8), grade B (n = 4), grade C (n = 1)), 1 hemorrhage (grade C). Postoperative mortality was 4% (n = 2), all following PD, caused by a massive intraoperative air embolism and by a multiple organ failure after anastomotic leakage. Pathological analysis confirmed pancreatic involvement in 17 (34%) specimens. Microscopically complete resection (R0) was achieved in 22 (44%) patients. After a follow-up of 60 months, 36 patients (75%) were still alive, among whom 27 without recurrence (56%).

CONCLUSION

Pancreatic resection during RPS surgery is associated with significant postoperative morbidity and mortality. PD should be avoided whenever possible while other procedures seemed achievable without excessive morbidity and with long-term survival.

[Differentiated surgical approach for retroperitoneal non-organ liposarcoma]

OBJECTIVE

To determine the indications for combined and organ-sparing surgery depending on malignancy grade of retroperitoneal liposarcoma.

MATERIAL AND METHODS

A retrospective study included 190 patients with retroperitoneal liposarcoma. Influence of malignancy grade, lesion of adjacent organs and resection/excision of adjacent organs on the overall and recurrence-free survival was studied. Moreover, we analyzed the issue of kidney-sparing surgery and nephrectomy.

RESULTS

Overall and recurrence-free survival were significantly worse in high grade (G2-3) compared to low-grade tumors (G1) (p=0.0001; log-rank test). Visceral invasion was revealed in 23% of patients with low-grade (G1) tumors and 53% of patients with high-grade (G2-3) neoplasms. Visceral invasion significantly impairs overall and recurrence-free survival in both low grade (G1) and high-grade (G2-3) tumors (p=0.0001; log-rank test). In case of low grade (G1) retroperitoneal liposarcoma, overall and recurrence-free survival was similar after combined surgery without histologically confirmed visceral invasion of liposarcoma and organ-sparing surgery (p=0.006; p=0.053; log-rank test). On the contrary, high grade (G2-3) tumor was followed by significantly better overall and recurrence-free survival after combined surgery without histologically confirmed visceral invasion compared to organ-sparing surgery (p=0.006; p=0.053; log-rank test). Recurrence-free survival was similar after kidney-sparing surgery and nephrectomy among patients with low-grade (G1) tumor (p=0.456; log-rank test). In case of high-grade retroperitoneal liposarcoma (G2-3), recurrence-free survival was significantly worse after kidney-sparing surgery compared to nephrectomy (p=0.039; log-rank test).

CONCLUSION

Surgery is the only potentially radical treatment of patients with retroperitoneal liposarcoma. Organ-sparing including kidney-sparing surgery is advisable for low-grade liposarcoma (G1). On the contrary, organ-sparing surgery impairs long-term results and prognosis in patients with high-grade tumors (G2-3). Combined operations including nephrectomy are justified for high-grade retroperitoneal liposarcoma (G2-3).

Radical Versus Non-Radical Resection for Early-Stage Retroperitoneal Sarcoma: A Propensity Score-Matched Analysis

Background

The appropriate surgical procedure for early-stage retroperitoneal sarcoma (RPS) is unclear. Thus, we used a national database to compare the outcomes of radical and non-radical resection in patients with early stage RPS.

Methods

This retrospective study included 886 stage I RPS patients from 2004 to 2015 in the SEER database. Outcomes were compared using the multivariate Cox proportional hazards models and the results were presented as adjusted hazards ratio (AHR) with corresponding 95% confidence intervals (95%CIs). Propensity score-matched analyses were also performed for sensitive analyses.

Results

For the 886 stage I RPS patients, 316 underwent radical resection, and 570 underwent non-radical resection, with a median follow-up of 4.58 (2.73-8.35) years. No difference was observed in overall mortality (AHR 0.84, 95%CI 0.62-1.15; P = 0.28) or RPS-specific mortality (AHR 0.88, 95%CI 0.57-1.36; P = 0.56) between groups. The results were similar in propensity score-matching analyses. However, subgroup analysis revealed that radical resection was associated with significantly decreased risks of overall mortality in male (AHR 0.61, 95%CI 0.38-0.98; P = 0.04) and in patients with radiotherapy (AHR 0.56, 95%CI 0.32-0.98; P = 0.04).

Conclusion

Radical resection did not improve midterm survival outcomes compared with non-radical resection in overall patients with early stage RPS. However, male patients or patients who received radiotherapy might benefit from radical resection with improved overall survival.

Retroperitoneal sarcoma: the Transatlantic Australasian Retroperitoneal Sarcoma Working Group Program

PURPOSE OF REVIEW

The Transatlantic Australasian Retroperitoneal Sarcoma Working Group (TARPSWG) is a bottom-up clinical network established in 2013 with the goal of improving the care and outcomes of patients with retroperitoneal sarcoma (RPS). Here, we review the knowledge produced by this collaborative effort and examine the future potential of this group.

RECENT FINDINGS

TARPSWG has produced retrospective studies focused on patients with primary and recurrent RPS allowing a better understanding of patient prognosis, treatment outcomes and tumor biology. The group has played a pivotal role in a phase III randomized STudy of preoperative RAdiotherapy plus Surgery versus surgery alone for patients with Retroperitoneal Sarcoma (STRASS) trial, favoring patient recruitment and trial completion. A prospective registry for patients with primary RPS populated by TARPSWG members is ongoing. TARPSWG has created consensus papers with recommendations regarding the management of patients with primary, recurrent and metastatic RPS that collated the views of representatives of sarcoma centers from Europe, North America, Asia and Australia.

SUMMARY

Since its inception, TARPSWG has become a leading network in the field of RPS. It has made a major contribution to the world of RPS research and cares allowing to overcome the limitations related to the rarity of the disease through collaboration.

Cumulative Burden of Postoperative Complications in Patients Undergoing Surgery for Primary Retroperitoneal Sarcoma

BACKGROUND

Correlations between postoperative complications and oncological outcomes have been reported in several malignancies, but their impact in retroperitoneal sarcoma (RPS) is unclear. Our study aimed to evaluate the association between postoperative complications and prognosis in patients with RPS.

METHODS

Patients undergoing surgery for primary RPS from 2008 to 2019 at a sarcoma center were evaluated. The cumulative burden of postoperative complications was quantified using the Comprehensive Complication Index (CCI), and associations with local recurrence (LR), distant metastases (DM) and overall survival (OS) were assessed.

RESULTS

Data were available for 191 patients, of whom 160 (82.9%) developed at least one postoperative complication, with a median CCI of 20.9 (interquartile range 8.7-33.5). After postoperative deaths were excluded (n = 3, 1.6%), the remaining patients were divided into those with a CCI of 0-20.9 (n = 97) and > 20.9 (n = 91). Patients with a CCI >20.9 had significantly shorter OS than those with a CCI of 0-20.9 (43.3% vs. 69.5% at 5 years; p = 0.005), and this difference remained significant after multivariable adjustment for patient- and treatment-related factors [hazard ratio (HR) 2.31, 95% confidence interval (CI) 1.30-4.09; p = 0.004]. However, CCI > 20.9 was not found to be a significant independent predictor of either LR (HR 1.30, 95% CI 0.76-2.23; p = 0.333) or DM (HR 1.08, 95% CI 0.61-1.93; p = 0.786).

CONCLUSION

Increasing complication burden, as quantified by the CCI, is a significant independent predictor of OS; however, there is no evidence of a significant association with either LR or DM, which may be more related to tumor biological factors.

Management of Primary Retroperitoneal Sarcoma (RPS) in the Adult: An Updated Consensus Approach from the Transatlantic Australasian RPS Working Group

BACKGROUND

Retroperitoneal soft tissue sarcomas comprise a heterogeneous group of rare tumors of mesenchymal origin that include several well-defined histologic subtypes. In 2015, the Transatlantic Australasian RPS Working Group (TARPSWG) published consensus recommendations for the best management of primary retroperitoneal sarcoma (RPS). Since then, through international collaboration, new evidence and knowledge have been generated, creating the need for an updated consensus document.

METHODS

The primary aim of this study was to critically evaluate the current evidence and develop an up-to-date consensus document on the approach to these difficult tumors. The resulting document applies to primary RPS that is non-visceral in origin, with exclusion criteria as previously described. The relevant literature was evaluated and an international group of experts consulted to formulate consensus statements regarding the best management of primary RPS. A level of evidence and grade of recommendation were attributed to each new/updated recommendation.

RESULTS

Management of primary RPS was considered from diagnosis to follow-up. This rare and complex malignancy is best managed by an experienced multidisciplinary team in a specialized referral center. The best chance of cure is at the time of primary presentation, and an individualized management plan should be made based on the 29 consensus statements included in this article, which were agreed upon by all of the authors. Whenever possible, patients should be enrolled in prospective trials and studies.

CONCLUSIONS

Ongoing international collaboration is critical to expand upon current knowledge and further improve outcomes of patients with RPS. In addition, prospective data collection and participation in multi-institution trials are strongly encouraged.

Myogenic dedifferentiation is associated with poor outcomes in retroperitoneal dedifferentiated liposarcomas

Sarcomas are a heterogenous group of malignant tumors with origin or mesenchymal differentiation, they comprise 1–2% of all solid tumors. Retroperitoneum is the second most frequent site affected. Prognosis is worse compared to the limbs, with a 5y OS of 36–58%, and 50–60% patients will relapse. Dedifferentiated liposarcomas (ddLPS) are more aggressive, it is known that presence of a de-differentiated component increases the probability of distant recurrence and lowers OS. There is little information about the specific impact of each type of de-differentiation. To determine if the presence of myogenic differentiation markers in DDLPS is an adverse prognostic factor. A retrospective, observational, analytic cohort study was performed. Cases identified from the electronic clinical files from the National Cancer Institute in Mexico City, we included cases from January 1st 2005 to December 31st 2016. We correlated the presence of expression of myogenic markers (Smooth muscle actin, Calponin, H-caldesmon, Desmin and Myogenin) in the dedifferentiated component of DDLPS with overall survival and surgical outcomes. One hundred and forty-three cases were analyzed. Eighty-two were liposarcomas, and 38 had a dedifferentiated component. Of these 38 cases, 21(55.3%) were males and, 17(44.7%) were females. Median age was 54.1(27–79) years, median tumor size was 28 cm (13–56). Most patients had locally advanced disease: 32(84.2%) were in stage IIIB. 2.6% had metastatic disease and 5(13.2%) had stage Ib at diagnosis. Myogenic marker expression was found in 18.4% of cases; these patients had a worse median survival than cases with no myogenic expression: 18 months (95% CI 15.4–20.5) vs 32 months (95% CI 21.8–42.1) p = 0.01, we also found a relation with higher postoperative morbidity in these cases (p = 0.045). The presence of myogenic differentiation markers might be associated with a worse prognosis, in our series it corelated with worse OS, however it is not a common event. Relation with surgical morbidity is to be analyzed in further studies.

Neoadjuvant irradiation of retroperitoneal soft tissue sarcoma with ions (Retro-Ion): study protocol for a randomized phase II pilot trial

Background

Following surgery for soft tissue sarcoma of the retroperitoneum, the predominant pattern of failure is local recurrence, which remains the main cause of death. Radiotherapy is utilized to reduce recurrence rates but the efficacy of this strategy has not been definitely established. As treatment tolerability is more favorable with preoperative radiotherapy, normofractionated neoadjuvant treatment is the current approach. The final results of the prospective, randomized STRASS (EORTC 62092) trial, which compared the efficacy of this combined treatment to that of surgery alone, are still awaited; preliminary results presented at the 2019 ASCO Annual Meeting indicated that combined treatment is associated with better local control in patients with liposarcoma (74.5% of the cohort, 11% benefit in abdominal progression free survival after 3 years, p = 0.049). Particles allow better sparing of surrounding tissues at risk, e.g., bowel epithelium, and carbon ions additionally offer biologic advantages and are preferred in slow growing tumors. Furthermore, hypofractionation allows for a significantly shorter treatment interval with a lower risk of progression during radiotherapy.

Methods and design

We present a prospective, randomized, monocentric phase II trial. Patients with resectable or marginally resectable, histologically confirmed soft tissue sarcoma of the retroperitoneum will be randomized between neoadjuvant proton or neoadjuvant carbon ion radiotherapy in active scanning beam application technique (39 Gy [relative biological effectiveness, RBE] in 13 fractions [5–6 fractions per week] in each arm). The primary objective is the safety and feasibility based on the proportion of grade 3–5 toxicity (CTCAE, version 5.0) in the first 12 months after surgery or discontinuation of treatment for any reason related to the treatment. Local control, local progression-free survival, disease-free survival, overall survival, and quality of life are the secondary endpoints of the study.

Discussion

The aim of this study is to confirm that hypofractionated, accelerated preoperative radiotherapy is safe and feasible. The rationale for the use of particle therapy is the potential for reduced toxicity. The data will lay the groundwork for a randomized phase III trial comparing hypofractionated proton and carbon ion irradiation with regard to local control.

Trial registration

ClinicalTrials.gov NCT04219202. Retrospectively registered on January 6, 2020

Diagnostic and management challenges for MDM2-, CDK4-negative fatty tumors of the retroperitoneum

BACKGROUND

Neoplasms of the retroperitoneum that contain a major fat component may represent either benign entities, such as lipomas or angiomyolipomas, or malignancy such as liposarcoma. Distinguishing these diagnoses has important implications for management. While liposarcomas often stain positively for MDM2 and CDK4 proteins, absence of these markers can lead to diagnostic and management challenges.

METHODS

We examined three cases in our institution of fat-containing masses of the retroperitoneum that lacked MDM2 and CDK4 markers to highlight the challenges in diagnosing and managing these cases. A thorough review of the literature examining radiologic and histologic features that can be used to determine that diagnosis was conducted and summarized.

RESULTS

The three cases we present represent the three main diagnostic entities that can be found in among fatty tumors of the retroperitoneum: lipoma, angiomyolipoma, and liposarcoma. While radiologic features and analysis of histology helped to inform management, these cases in conjunction with the literature also illustrate the limitations of the diagnostic work up and importance also factoring the biologic behavior of the tumor in its management.

CONCLUSION

Fat-containing tumors of the retroperitoneum that do not stain for MDM2 or CDK4 can pose a diagnostic challenge. Assessing radiologic and pathologic features in conjunction with the biologic behavior of these tumors should inform their management.