Retroperitoneal Sarcoma

CT and MR Imaging of Retroperitoneal Sarcomas: A Practical Guide for the Radiologist

Primary retroperitoneal sarcomas (RPS) represent around 10-16% of all sarcomas, with liposarcomas and leiomyosarcomas being the most common subtypes. RPS have some peculiar characteristics, imaging appearances, worse prognosis, and complications compared to other locations of sarcoma. Commonly, RPS primarily present as large masses, progressively encasing adjacent structures, causing mass effect, and complications. RPS diagnosis is often challenging, and these tumors may be overlooked; however, failure to recognize RPS characteristics leads to a worse prognosis for the patients. Surgery is the only recognized curative treatment, but the anatomical constraints of the retroperitoneum limit the ability to achieve wide resection margins; therefore, these tumors have a high rate of recurrence, and require long-term follow-up. The radiologist has an important role in the diagnosis of RPS, the definition of their extent, and their follow-up. Specific knowledge of the main imaging findings is required to reach an early diagnosis, and, ultimately, to guarantee the best patient management. This article provides an overview of the current knowledge regarding cross-sectional imaging features of patients with retroperitoneal sarcomas, presenting tips and tricks to improve imaging diagnosis of RPS.

Survival outcomes of surgery for retroperitoneal sarcomas: A systematic review and meta-analysis

Background

Definitive evidence to guide clinical practice on the principles of surgery for retroperitoneal sarcomas (RPSs) is still lacking. This study aims to summarise the available evidence to assess the relative benefits and disadvantages of an aggressive surgical approach with contiguous organ resection in patients with RPS, the association between surgical resection margins and survival outcomes, and the role of surgery in recurrent RPS.

Methods

We searched PubMed, the Cochrane Library, and EMBASE for relevant randomised trials and observational studies published from inception up to May 1, 2021. Prospective or retrospective studies, published in the English language, providing outcome data with surgical treatment in patients with RPS were selected. The primary outcome was overall survival (OS).

Findings

In total, 47 articles were analysed. There were no significant differences in the rates of OS (HR: 0.93; 95% CI: 0.83–1.03; P = 0.574) and recurrence-free survival (HR: 1.00; 95% CI: 0.74–1.27; P = 0.945) between the extended resection group and the tumour resection alone group. Organ resection did not increase postoperative mortality (OR: 1.00; 95% CI: 0.55–1.81; P = 0.997) but had a relatively higher complication rate (OR: 2.24, 95% CI: 0.94–5.34; P = 0.068). OS was higher in R0 than in R1 resection (HR: 1.34; 95% CI: 1.23–1.44; P < 0.001) and in R1 resection than in R2 resection (HR: 1.86; 95% CI: 1.35–2.36; P < 0.001). OS was also higher in R2 resection than in no surgery (HR: 1.26; 95% CI: 1.07–1.45; P < 0.001), however, subgroup analysis showed that the pooled HR in the trials reporting primary RPS was similar between the two groups (HR, 1.14; 95% CI, 0.87–1.42; P = 0.42). Surgical treatment achieves a significantly higher OS rate than does conservative treatment (HR: 2.42; 95% CI: 1.21–3.64; P < 0.001) for recurrent RPS.

Conclusions

For primary RPS, curative-intent en bloc resection should be aimed, and adjacent organs with evidence of direct invasion must be resected to avoid R2 resection. For recurrent RPS, surgical resection should be considered as a priority. Incomplete resection remains to have a survival benefit in select patients with unresectable recurrent RPS.

The evolution of adjuvant/neoadjuvant trials for resectable localized sarcoma

Soft-tissue sarcomas are rare tumors arising from mesenchymal tissues. As a heterogeneous group comprising more than 50 types, the development of clinical trials remains challenging. Decision-making for neoadjuvant or adjuvant chemotherapy and radiation therapy is based on the available evidence of contemporary trials and multidisciplinary clinical judgment.

[Treatment of recurrent retroperitoneal myxolipoma]

The problem of retroperitoneal neoplasm management is still relevant despite certain achievements in diagnosis, anesthetic care and surgical techniques. These patients often admit to specialized hospitals with a widespread malignant process and/or complications due to no specific symptoms. Resection is preferred for malignant inorganic retroperitoneal tumors. A feature of these neoplasms is frequent local relapses, which seriously limit the possibility of redo surgery. The authors report successful surgical treatment of recurrent malignant inorganic retroperitoneal myxolipoma with giant baseline dimensions.

Outcome after surgical resection of multiple recurrent retroperitoneal soft tissue sarcoma

INTRODUCTION

Local recurrences (LR) and distant metastases (DM) are common in retroperitoneal soft tissue sarcoma (RPS). Longer time to recurrence and resection of the recurrent lesion have been identified as beneficial prognostic factors for overall survival (OS) upon first tumor relapse. However, prognostic factors concerning OS upon subsequent recurrences are scarcely defined. In this study, we aimed to identify prognostic factors for post-relapse outcome in multiple recurrent RPS.

METHODS

Patients undergoing resection of primary and recurrent RPS at the University Hospital Heidelberg were retrospectively analyzed. Multivariable Cox regression analyses were performed to identify predictors of overall, LR- and DM-free survival. Subgroup analyses were performed for liposarcoma and leiomyosarcoma patients.

RESULTS

201 patients with primary disease, 101 patients with first, 66 patients with second and 43 patients with third LR as well as 75 patients with DM were analyzed. More than 12 months to recurrence and resection of recurrence were associated with improved OS after resection of first and second LR (5-year OS for first/second LR; resection: 64%/62%, no resection: 20%/46%). Gross macroscopic incomplete resection of first (p < 0.001), second (p = 0.001), and third recurrences (p < 0.001) was an independent prognostic factor for poor OS.

CONCLUSION

Development of LR and DM is frequent in RPS. Once a tumor relapsed, patients benefit from tumor resection not only in case of first, but also in case of subsequent recurrences.

Significance of intraoperative radiation therapy and high cumulative radiation doses in retroperitoneal soft tissue sarcoma

INTRODUCTION

In retroperitoneal soft tissue sarcoma (STS) local recurrence (LR) rates remain high despite more aggressive surgical approaches. Since wide resection margins cannot be achieved in all patients, application of intraoperative radiation therapy (IORT) has been frequently discussed. Still, the significance of IORT in multimodal treatment of retroperitoneal STS remains unclear.

MATERIAL AND METHODS

Patients undergoing resection of primary or recurrent retroperitoneal STS at the University of Heidelberg Department of General, Visceral and Transplantation Surgery were retrospectively analyzed. Univariate Kaplan-Meyer and multivariate Cox regression analyses were performed to identify predictors of LR-free survival and to investigate the impact of IORT and high cumulative radiation doses. Analyses with propensity-score matched subgroups for IORT and cumulative radiation dose were performed to control for selection bias. Subgroup analyses for patients with retroperitoneal liposarcoma were likewise performed.

RESULTS

272 patients were identified. Recurrent tumors, histology of dedifferentiated liposarcoma or unclassified sarcoma and microscopically incomplete resection were associated with decreased LR-free survival. In liposarcoma, only recurrent and dedifferentiated tumors were confirmed as poor prognostic factors concerning LR. IORT and cumulative radiation doses exceeding 60 Gy did not influence LR rates (estimated 5-year LR-free survival: IORT: 39%, non-IORT: 46%; p = 0.79).

CONCLUSION

In this retrospective evaluation, additional application of IORT does not significantly influence oncological outcome in retroperitoneal soft tissue sarcoma. Randomized trials are needed to clarify the benefit of IORT.

Management of the "Other" retroperitoneal sarcomas

The focus of this review is on the management of the less common sarcomas occurring in the retroperitoneal space, including solitary fibrous tumor (SFT), malignant peripheral nerve sheath tumor (MPNST), perivascular epithelioid cell tumor (PEComa), and undifferentiated pleomorphic sarcoma (UPS) of the psoas muscle. As for other retroperitoneal sarcomas, surgical resection is the mainstay of curative therapy, and multidisciplinary preoperative assessment, including percutaneous needle biopsy for histologic confirmation, is the basis for personalized management, as the surgical management, and the integration of systemic therapy and radiation therapy is unique to each histologic subtype.

Treatment of retroperitoneal sarcoma: current standards and new developments

PURPOSE OF REVIEW

Retroperitoneal sarcomas are rare tumors and with complex treatment. In this manuscript we give an overview of current standards in treatment of this disease and discuss new developments.

RECENT FINDINGS

Surgery with complete resection of the primary tumor is still the only curative modality. The role of preoperative radiotherapy is not clear and is currently being investigated in a clinical trial. Neo-adjuvant chemotherapy is not the standard of care but can be considered occasionally when complete resection is uncertain. Local and distant recurrent disease carries a dismal prognosis, although long-term survival can be achieved. Liposarcomas tend to recur locally, whereas distant recurrences are more often seen in leiomyosarcoma and other subtypes. Outcome improves when patients are treated in high volume sarcoma centers. In the metastatic setting, newer systemic agents have recently been approved.

SUMMARY

Treatment of retroperitoneal sarcomas is complex and all patients should be treated in multidisciplinary sarcoma centers. Increasing international collaboration of expert centers in sharing expertise and performing clinical trials might lead to better treatment and improved survival.

CDK4/6 Inhibitors Sensitize Rb-positive Sarcoma Cells to Wee1 Kinase Inhibition through Reversible Cell-Cycle Arrest

Research into the biology of soft tissue sarcomas has uncovered very few effective treatment strategies that improve upon the current standard of care which usually involves surgery, radiation, and chemotherapy. Many patients with large (>5 cm), high-grade sarcomas develop recurrence, and at that point have limited treatment options available. One challenge is the heterogeneity of genetic drivers of sarcomas, and many of these are not validated targets. Even when such genes are tractable targets, the rarity of each subtype of sarcoma makes advances in research slow. Here we describe the development of a synergistic combination treatment strategy that may be applicable in both soft tissue sarcomas as well as sarcomas of bone that takes advantage of targeting the cell cycle. We show that Rb-positive cell lines treated with the CDK4/6 inhibitor palbociclib reversibly arrest in the G1 phase of the cell cycle, and upon drug removal cells progress through the cell cycle as expected within 6-24 hours. Using a long-term high-throughput assay that allows us to examine drugs in different sequences or concurrently, we found that palbociclib-induced cell-cycle arrest poises Rb-positive sarcoma cells (SK-LMS1 and HT-1080) to be more sensitive to agents that work preferentially in S-G2 phase such as doxorubicin and Wee1 kinase inhibitors (AZD1775). The synergy between palbociclib and AZD1775 was also validated in vivo using SK-LMS1 xenografts as well as Rb-positive patient-derived xenografts (PDX) developed from leiomyosarcoma patients. This work provides the necessary preclinical data in support of a clinical trial utilizing this treatment strategy. Mol Cancer Ther; 16(9); 1751-64. ©2017 AACR.

Neoadjuvant chemotherapy in soft tissue sarcomas: latest evidence and clinical implications

Soft tissue sarcomas are a rare and multifaceted group of solid tumours. Neoadjuvant chemotherapy is increasingly used to limit loss of function after wide surgical excision with the ultimate aim of improving patient survival. Recently, advances in the identification of effective treatment strategies and improvements in patient risk stratification have been reached. A randomized trial demonstrated that neoadjuvant epirubicin and ifosfamide improves survival of patients affected by five high-risk soft tissue sarcoma histologies of trunk and extremities, including undifferentiated pleomorphic sarcoma, myxoid liposarcoma, synovial sarcoma, malignant peripheral nerve sheath tumours, and leiomyosarcoma. Selection of patients for these treatments is expected to be improved by the eighth edition of the American Joint Committee on Cancer (AJCC) TNM staging system, as it tailors T-stage categories on primary tumour site and considers a prognostic nomogram for retroperitoneal sarcoma, which also includes soft tissue sarcoma histology and other patient and tumour features not directly included in the TNM staging. Within this framework, this article will present neoadjuvant treatment strategies for high-risk soft tissue sarcoma, emphasizing the most recent advances and discussing the need for further research to improve the effectiveness of neoadjuvant treatments.