Has the Outcome for Patients Who Undergo Resection of Primary Retroperitoneal Sarcoma Changed Over Time? A Study of Time Trends During the Past 15 years

New Sarculator Prognostic Nomograms for Patients With Primary Retroperitoneal Sarcoma: Case Volume Does Matter

OBJECTIVE

To update the current Sarculator retroperitoneal sarcoma (RPS) prognostic nomograms considering the improvement in patient prognosis and the case volume effect.

BACKGROUND

Survival of patients with primary RPS has been increasing over time, and the volume-outcome relationship has been well recognized. Nevertheless, the specific impact on prognostic nomograms is unknown.

METHODS

All consecutive adult patients with primary localized RPS treated at 8 European and North American sarcoma reference centers between 2010 and 2017 were included. Patients were divided into 2 groups: high-volume centers (HVC, ≥13 cases/year) and low-volume centers (LVC, <13 cases/year). Primary end points were overall survival (OS) and disease-free survival (DFS). Multivariable analyses for OS and DFS were performed. The nomograms were updated by recalibration. Nomograms performance was assessed in terms of discrimination (Harrell C index) and calibration (calibration plot).

RESULTS

The HVC and LVC groups comprised 857 and 244 patients, respectively. The median annual primary RPS case volume (interquartile range) was 24.0 in HVC (15.0-41.3) and 9.0 in LVC (1.8-10.3). Five-year OS was 71.4% (95% CI: 68.3%-74.7%) in the HVC cohort and 63.3% (56.8%-70.5%) in the LVC cohort ( P =0.012). Case volume was associated with both OS (LVC vs. HVC hazard ratio 1.40, 95% CI: 1.08-1.82, P =0.011) and DFS (hazard ratio 1.93, 95% CI: 1.57-2.37, P <0.001) at multivariable analyses. When applied to the study cohorts, the Sarculator nomograms showed good discrimination (Harrell C index between 0.68 and 0.73). The recalibrated nomograms showed good calibration in the HVC group, whereas the original nomograms showed good calibration in the LVC group.

CONCLUSIONS

New nomograms for patients with primary RPS treated with surgery at high-volume versus low-volume sarcoma reference centers are available in the Sarculator app.

What is the association of preoperative biopsy with recurrence and survival in retroperitoneal sarcoma? A systematic review by the Australia and New Zealand Sarcoma Association clinical practice guidelines working party

Preoperative biopsy for retroperitoneal sarcoma (RPS) enables appropriate multidisciplinary treatment planning. A systematic review of literature from 1990 to June 2022 was conducted using the population, intervention, comparison and outcome model to evaluate the local recurrence and overall survival of preoperative biopsy compared to those that had not. Of 3192 studies screened, five retrospective cohort studies were identified. Three reported on biopsy needle tract seeding, with only one study reporting biopsy site recurrence of 2 %. Two found no significant difference in local recurrence and one found higher 5-year local recurrence rates in those who had not been biopsied. Three studies reported overall survival, including one with propensity matching, did not show a difference in overall survival. In conclusion, preoperative core needle biopsy of RPS is not associated with increased local recurrence or adverse survival outcomes.

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.

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.

The role of radiation therapy in the management of primary retroperitoneal sarcoma: A systematic review and clinical practice guidelines from the Australia and New Zealand Sarcoma Association

While surgery is the mainstay of treatment for localised retroperitoneal sarcoma, the use of radiotherapy (RT) remains controversial. This systematic review aimed to evaluate the role of RT for retroperitoneal sarcoma. A systematic review using the population, intervention, comparison, and outcome model from 1990 to 2022 identified 66 studies (a mixture of preoperative and postoperative RT); one randomised controlled trial (RCT) with two publications, 18 registry studies, and 46 retrospective studies. In the RCT of preoperative RT, there was no difference in local/abdominal recurrence. The pooled analysis of this RCT and a retrospective study showed a significant abdominal recurrence free survival benefit with preoperative RT in low grade liposarcoma. The RCT and the majority of retrospective series found RT did not improve recurrence free survival (11 of 16 no difference in combined local and distant RFS, 11 of 13 no difference in distant metastasis free survival), disease specific survival (9 of 12 studies) or overall survival (33 of 49 studies). The majority of studies found no association between RT and perioperative morbidity. In summary, preoperative RT may improve local control for low grade (well-differentiated or grades 1-2 dedifferentiated) liposarcoma, but not other histological subtypes. There is no strong evidence that perioperative RT provides an overall survival benefit. Patients with low grade retroperitoneal liposarcoma can be considered for preoperative RT to improve abdominal recurrence free survival. The rationale and level of evidence in this scenario should be carefully discussed by the multidisciplinary team with patients. RT should not be routinely recommended for other histological subtypes.

Long-term quality of life after resection of retroperitoneal soft tissue sarcoma

INTRODUCTION

Retroperitoneal soft tissue sarcoma (RPS) is characterized by high recurrence rates. Since complete tumor resection, often necessitating multivisceral resection, enables long-term survival in both primary and recurrent disease, health related quality of life (QoL) after RPS resection has attracted increasing interest. However, data regarding this topic is limited. Here, we multidimensionally assessed long-term QoL after RPS resection.

METHODS

Five previously validated (1. EORTC QLQ-C30, 2. WEMWBS, 3. FoP-Q-SF, 4. PC-PTSD, 5. Pro-CTCAE) were sent to patients having undergone resection of primary, recurrent and metastasized RPS at Heidelberg University Hospital between 10/2001 and 12/2020. Multivariable linear regression models were used to test associations between clinical/demographic variables and patient reported outcomes (PROs).

RESULTS

Questionnaires were answered by 127 patients (71% response rate). The median interval between RPS diagnosis and assessment of PROs was 80 months. The overall Global Health score was 64.1 and comparable to the general German population. RPS patients reported deficits regarding emotional and social functioning, whereas physical limitations were less pronounced. Besides diarrhea, abdominal symptoms were comparable to the overall population. Tumor recurrences, the number of surgeries, multivisceral resections or postoperative complications did not significantly affect long-term QoL ratings.

CONCLUSION

RPS patients rate their QoL relatively high, even after multiple and multivisceral resections. Psychosocial well-being should be monitored in follow-up sessions to offer tailored support if necessary, thus improving postoperative care.

Risk Factors for the Development of Early Recurrence in Patients with Primary Retroperitoneal Sarcoma

BACKGROUND

Disease recurrence after retroperitoneal sarcoma (RPS) surgery is common, and resection may offer no benefit for patients who experience recurrence early. This study examined the incidence of early recurrence (EREC) in RPS patients, and the association between EREC and prognosis, aiming to identify the factors associated with EREC.

METHODS

Patients undergoing surgery for primary RPS from 2008 to 2019 at two tertiary RPS centers were analyzed. The study defined EREC as any evidence of local recurrence and/or distant metastases on the CT scan up to 6 months after surgery. Overall survival (OS) was calculated using the Kaplan-Meier method. A multivariable analysis was performed to identify independent predictors of EREC.

RESULTS

Of the 692 patients who underwent surgery during the study period, 657 were included in the analysis. Sixty-five of these patients (9.9%; 95% confidence interval [CI], 7.7-12.4%) developed EREC. Five-year OS was 3% for the patients with EREC versus 76% for those without EREC (p < 0.001). Patient characteristics were compared between the EREC and non-EREC patients, and EREC was found to be significantly associated with Eastern Cooperative Oncology Group (ECOG) performance status (p = 0.006), tumor histology (p = 0.002), tumor grading (p < 0.001), radiotherapy (p = 0.04), and postoperative complications measured as a comprehensive complications index value (p = 0.003). However, the only significant independent predictor of EREC in the multivariable analysis was grade 3 tumors, with an odds ratio of 14.8 (95% CI, 4.44-49.2; p < 0.001).

CONCLUSION

Early recurrence is associated with a poor prognosis, and a high tumor grade is an independent predictor for the development of EREC. Patients with EREC may benefit the most from new therapeutic options such as neoadjuvant chemotherapy.

A century of retroperitoneal soft-tissue sarcoma research: From single center experience to precision oncology? A bibliometric analysis of past, present, and future perspectives

BACKGROUND

Increasing publication numbers in the biomedical field led to an improvement of patient care in many aspects but are challenging for scientists when integratively processing data of their fields. Using bibliometric analyses, the present study assesses the productivity and predominant topics in retroperitoneal soft-tissue sarcoma (RPS) research across the past 122 years, thereby identifying crucial questions to address in future RPS research.

METHODS

Using the Web of Science Core Collection, 1018 RPS-associated publications from 1900 to 2022 were identified and analyzed regarding key bibliometric variables using the Bibliometrix R package and the VOSviewer software.

RESULTS

A continuous increase in RPS-associated publication numbers can be noticed over the time, which is strongly pronounced from 2005 onwards, and is characterized by a multinationally driven collaborative clinical research focus. The research primarily reflects progression regarding surgical techniques, histology-based therapy, radiotherapy regimens, and identification of prognostic clinicopathological factors. This progression is accompanied with improved overall survival of RPS patients. However, a paucity of RPS-specific basic/translational research indicates that such research might be additionally needed to better understand the pathophysiology of RPS and with that to enable the development of personalized therapies and to further improve patient outcome.

CONCLUSION

Increasing publication numbers of multinationally driven clinical RPS research are accompanied with improved overall survival of RPS patients, highlighting the importance of international collaborations to facilitate future clinical trials. However, this bibliometric analysis reveals a lack of RPS-specific basic/translational research which is needed to further improve patient outcome in the context of precision oncology.

Deciding individual treatment for primary retroperitoneal sarcoma

INTRODUCTION

Retroperitoneal sarcomas (RPS) are rare mesenchymal tumors that account for only 0.1-0.2% of all malignancies. Management of this disease is challenging, and resection remains the cornerstone of treatment. Ongoing international collaboration has expanded our knowledge of this disease, allowing for a more personalized approach to RPS patients resulting in improved survival over time. Due to the heterogeneity of RPS, with differing recurrence patterns and sensitivities to neoadjuvant therapies based on histology and grade, management of RPS should be tailored to the individual patient.

AREAS COVERED

Our review focuses on a histology-driven approach in the management of primary RPS. We searched relevant articles from 1993 to 2023 that investigated prognostic factors and treatment of patients with RPS and summarized recent advances and future directions in the field.

EXPERT OPINION

Deeper understanding of the role of neoadjuvant radiotherapy and ongoing trials investigating the role of neoadjuvant chemotherapy will potentially contribute to the development of individualized treatment pathways.

Follow-up of patients with retroperitoneal sarcoma

Retroperitoneal sarcomas (RPS) are rare malignancies that are potentially curable by complete surgical resection. A regular surveillance program is normally commenced following surgery due to the risk of local recurrence (LR), especially in low-intermediate grade disease, and distant metastases (DM), especially in high-grade RPS. Consensus guidelines usually advocate for more frequent imaging during the first 2-3 years and less intensive imaging over a prolonged period thereafter, reflecting the incidence pattern of LR and DM. Definitive evidence for the most effective imaging schedule has never been provided, and retrospective studies have not shown an association between follow-up intensity and survival. Improvement in the prediction of recurrence patterns has been sustained by prognostic dynamic nomograms, which are now capable of forecasting disease behaviour in each patient according to specific features. Incorporation of such tools in clinical practice may help to stratify patients and tailor ongoing surveillance to the risk of recurrence. This may help to relieve patients' anxiety while awaiting results of surveillance investigations, and also reduce the economic and environmental burden of repeated imaging. A randomized controlled study (SARveillance Trial) is proposed to shed light on this controversial topic, allowing clinicians to harmonize the follow-up protocol of patients undergoing surgery for RPS.

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.

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.

Staging Systems and Nomograms for Soft Tissue Sarcoma

Reliable tools for prognosis prediction are crucially needed by oncologists so they can tailor individual treatments. However, the wide spectrum of histologies and prognostic behaviors of sarcomas challenges their development. In this field, nomograms could definitely better account for their granularity compared to the more widely used AJCC/UICC TNM staging system. Nomograms are predictive tools that incorporate multiple risk factors and return a numerical probability of a clinical event. Since the development of the first nomogram in 2002, several other nomograms have been built, either general, site-specific, histology-specific, or both. Recently, some new “dynamic” nomograms and prognostic tools have been developed, allowing doctors to “recalculate” a patient’s prognosis by taking into account the time since primary surgery, the event history, and the potential time-dependent effect of covariates. Due to these new tools, prognosis prediction is no longer limited to the time of the first computation but can be adapted and recalculated based on the occurrence (or not) of any event as time passes from the first computation. In this review, we aimed to give an overview of the available nomograms for STS and to help clinicians in the process of selecting the best tool for each patient.

Key performance indicators for improving outcomes from retroperitoneal sarcoma surgery in New Zealand

BACKGROUND

Retroperitoneal sarcomas are a rare and heterogenous group of tumours. There is increasing evidence that high volume sarcoma units achieve superior outcomes than low volume units. Due to the relatively small population, New Zealand is unlikely to generate a sufficient case volume to be considered high volume. To our knowledge, no well-established key performance indicators (KPIs) exist for retroperitoneal sarcoma surgery. In order to ensure quality standards we aim to propose KPIs which will act as a benchmark and a target for future quality improvement.

METHODS

Potential KPIs were generated by internal discussion within the sarcoma team, taking into consideration available guidelines and evidence. Cases treated through the unit since 2015 were audited to determine historical performance against these KPIs.

RESULTS

Eighty-six patients with primary retroperitoneal sarcomas were identified. 69% of patients were discussed at the sarcoma MDM prior to treatment, 62% underwent preoperative core biopsy. 82% of patients were seen and treated within target timeframes set by the Ministry of Health. 53% of patients underwent surgery with a sarcoma trained surgeon. R0/R1 rate was 88%. 90-day mortality was 4.6%.

CONCLUSIONS

Surgical treatment of retroperitoneal sarcomas is complex and can be associated with significant morbidity. The proposed KPIs provide a measure of service performance and provide targets for quality improvement.

Surveillance Post Surgery for Retroperitoneal Soft Tissue Sarcoma

Complete en bloc surgical resection offers the best opportunity for the cure of primary retroperitoneal sarcomas (RPS). The potential for disease recurrence, in the form of both loco-regional recurrence and distant metastases, underpins the rationale for postoperative surveillance. There is a paucity of high-quality evidence underpinning follow-up for RPS patients, and most practice guidelines draw from expert opinion and evidence from soft tissue sarcomas of the extremities. The available observational retrospective data analysis has failed to demonstrate that high-intensity radiological surveillance improves the overall survival in patients. The lack of a robust evidence base has given rise to variations in approaches to post-operative surveillance strategies adopted by specialist centres managing RPS across the world. More high-quality prospective research is needed and planned to more clearly support surveillance approaches that balance oncologic outcomes, patient-centric care, and health service value. Risk stratification tools exist and are available for use in routine practice. Their use will likely support more individualised post-operative surveillance moving forward. Surveillance will likely be underpinned by serial radiological imaging for the medium term. However, developments in genomics offer hope for biomarkers such as ctDNA to impact patient care positively in the future and further support individualised patient care pathways.

Surgical Principles of Primary Retroperitoneal Sarcoma in the Era of Personalized Treatment: A Review of the Frontline Extended Surgery

Simple Summary

Surgery is the only curative treatment for localized disease in retroperitoneal sarcoma (RPS). Frontline extended surgery, or compartmental surgery, is a recent surgical strategy consisting of resecting the tumor together with adjacent organs, with the aim of minimizing marginality. This review provides a practical step by step description of this standardized procedure, tailored to histologic behavior, tumor localization, and patient condition.

Abstract

Surgery is the key treatment in retroperitoneal sarcoma (RPS), as completeness of resection is the most important prognostic factor related to treatment. Compartmental surgery/frontline extended approach is based on soft-tissue sarcoma surgical principles, and involves resecting adjacent viscera to achieve a wide negative margin. This extended approach is associated with improved local control and survival. This surgery must be tailored to tumor histology, tumor localization, and patient performance status. We herein present a review of compartmental surgery principles, covering the oncological and technical basis, and describing the tailored approach to each tumor subtype and localization in the retroperitoneum.

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.

Role of Radiation Therapy in Retroperitoneal Sarcoma

Retroperitoneal sarcoma comprises a small subset of all soft tissue sarcoma and includes various histopathologic subtypes, each with unique patterns of behavior and differential risks for local recurrence and hematogenous metastatic spread. The primary treatment modality is surgery, although even with complete macroscopic resection, recurrence is common. The rationale for the addition of radiotherapy to resection is to improve local control; however, the use of radiation therapy for retroperitoneal sarcoma is controversial, and existing data are suboptimal to guide management. Treatment decisions should be determined with multidisciplinary input and shared decision-making. When used in selected patients, radiation therapy should be delivered preoperatively; postoperative treatment is not recommended.

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.

Management of Locally Recurrent Retroperitoneal Sarcoma in the Adult: An Updated Consensus Approach from the Transatlantic Australasian Retroperitoneal Sarcoma Working Group

BACKGROUND

Surgery is the mainstay of treatment for retroperitoneal sarcoma (RPS), but local recurrence is common. Biologic behavior and recurrence patterns differ significantly among histologic types of RPS, with implications for management. The Transatlantic Australasian RPS Working Group (TARPSWG) published a consensus approach to primary RPS, and to complement this, one for recurrent RPS in 2016. Since then, additional studies have been published, and collaborative discussion is ongoing to address the clinical challenges of local recurrence in RPS.

METHODS

An extensive literature search was performed, and the previous consensus statements for recurrent RPS were updated after review by TARPSWG members. The search included the most common RPS histologic types: liposarcoma, leiomyosarcoma, solitary fibrous tumor, undifferentiated pleomorphic sarcoma, and malignant peripheral nerve sheath tumor.

RESULTS

Recurrent RPS management was evaluated from diagnosis to follow-up evaluation. For appropriately selected patients, resection is safe. Nomograms currently are available to help predict outcome after resection. These and other new findings have been combined with expert recommendations to provide 36 statements, each of which is attributed a level of evidence and grade of recommendation. In this updated document, more emphasis is placed on histologic type and clarification of the intent for surgical treatment, either curative or palliative. Overall, the fundamental tenet of optimal care for patients with recurrent RPS remains individualized treatment after multidisciplinary discussion by an experienced team with expertise in RPS.

CONCLUSIONS

Updated consensus recommendations are provided to help guide decision-making for treatment of locally recurrent RPS and better selection of patients who would potentially benefit from surgery.

Telomere as a Therapeutic Target in Dedifferentiated Liposarcoma

BACKGROUND

Well-differentiated (WD)/dedifferentiated (DD) liposarcoma (LPS) accounts for ~60% of retroperitoneal sarcomas. WDLPS and DDLPS divergently evolve from a common precursor and are both marked by the amplification of the 12q13-q15 region, leading to the abnormal expression of MDM2, CDK4, and HMGA2 genes. DDLPS is a non-lipogenic disease associated with aggressive clinical behavior. Patients have limited therapeutic options, especially for advanced disease, and their outcome remains largely unsatisfactory. This evidence underlines the need for identifying and validating DDLPS-specific actionable targets to design novel biology-driven therapies.

METHODS

Following gene expression profiling of DDLPS clinical specimens, we observed the up-regulation of "telomere maintenance" (TMM) pathways in paired DD and WD components of DDLPS. Considering the relevance of TMM for LPS onset and progression, the activity of a telomeric G-quadruplex binder (RHPS4) was assessed in DDLPS patient-derived cell lines.

RESULTS

Equitoxic concentrations of RHPS4 in DDLPS cells altered telomeric c-circle levels, induced DNA damage, and resulted in the accumulation of γ-H2AX-stained micronuclei. This evidence was paralleled by an RHPS4-mediated reduction of in vitro cell migration and induction of apoptosis/autophagy.

CONCLUSIONS

Our findings support telomere as an intriguing therapeutic target in DDLPS and suggest G-quadruplex binders as innovative therapeutic agents.

Immunotherapy in soft tissue sarcoma: current evidence and future perspectives in a variegated family of different tumour

INTRODUCTION

In the last few years steps forward in the knowledge of the biology of soft tissue sarcomas (STS) has led to the development of new therapeutic strategies, including immunotherapy.

AREAS COVERED

This review outlines the recent findings on immunological features and provides a synopsis of the results of clinical trials with different immunotherapy approaches in STS, discussing criticisms and how the efficacy of immunotherapy could be improved.

EXPERT OPINION

The heterogeneity of STS has limited generalized approaches of immunotherapy in the disease. Clinical decisions should encompass a comprehensive characterization of the tumour microenvironment (TME), marked by intra-histotype diversity. Profiling of immune cells, checkpoint molecules and antigen target/HLA expression is deemed to re-shape the classical histotype classification for a selection of the most appropriate immune-based treatment. In a synergistic view, tumour-directed treatments, designed on the genetic and epigenetic histotype make-up, should be monitored for their immunomodulant effect and applied to ensure or amplify immunotherapy response. In light of the dynamic nature of the TME, this immunomonitoring should be conducted at baseline and during treatment, for improved therapeutic decisions and rational sequence of treatment combination, pursuing an immunological marker approach by histotype guidance.

Delayed Gastric Emptying After Multivisceral Resection for Retroperitoneal Sarcoma

INTRODUCTION

Delayed gastric emptying (DGE) is a common complication in surgery, but incidence and relevance following multivisceral resection are unknown.

METHODS

Data from 100 consecutive patients treated for primary retroperitoneal sarcoma (RPS) were analyzed from our institutional prospectively maintained database from January 2019 to April 2020. DGE severity was graded according to the International Study Group of Pancreatic Surgery and classified as primary or secondary to other complications. The primary outcome was incidence and grade of clinically relevant DGE (grades B-C). Secondary outcomes were correlation with patient, tumor, and treatment characteristics, and non-DGE morbidity [Clavien-Dindo (CD) grade ≥ 3].

RESULTS

Forty-two patients developed DGE and 28 had clinically relevant DGE. DGE was primary in 10 patients and secondary in 18 patients; the most common associated complications were: infections (11/18, 61.1%), pancreatic leak (7/18, 38.9%), bleeding (6/18, 33.3%), and bowel leak (6/18, 33.3%). DGE was related to longer length of hospital stay (P < 0.001), ICU admission (P = 0.004), ICU length of stay (P = 0.001), postoperative complications (CD [Formula: see text] 3 in 14/28 in DGE patients vs 11/72 in no-DGE; P = 0.04), and re-operation (P = 0.03). With multivariate analysis, the independent risk factors for DGE were patient comorbidities (OR 1.05; 95% CI 1.01-1.1; P = 0.04) and tumor size (OR 1.05; 95% CI 1.0-1.1; P = 0.02).

DISCUSSION

Following multivisceral resection, DGE is a clinically relevant event that can be caused by an underlying complication. Prompt diagnosis and treatment of both DGE and any underlying complications led to full recovery in all cases.

[Retroperitoneal soft tissue sarcoma: surgical management]

BACKGROUND

Retroperitoneal soft tissue sarcomas are rare and heterogeneous tumors with high recurrence rates that require a multimodal treatment approach and a surgical resection strategy adapted to tumor localization and histological subtype.

OBJECTIVE

Based on current scientific data this article intends to provide an overview on subtype-specific features, prognostic factors and operative techniques in the surgical management of retroperitoneal soft tissue sarcomas.

MATERIAL AND METHODS

A review of the literature addressing surgical management of retroperitoneal soft tissue sarcomas was performed. Current evidence and recommendations were summarized.

RESULTS AND CONCLUSION

Macroscopically complete tumor resection represents the sole curative treatment option for both primary and recurrent retroperitoneal soft tissue sarcomas. To minimize the probability of tumor-infiltrated resection margins, compartmental resection has become a standard treatment for retroperitoneal soft tissue sarcomas. This approach includes resection of all organs and structures adjacent to the tumor. Multivisceral resection is often associated with this approach and it is acceptable in terms of morbidity and mortality if performed at a center with experience in retroperitoneal sarcoma surgery. Histologic subtype, tumor grading, and quality of initial surgical treatment are major prognostic factors for oncologic overall survival.

Longitudinal prognostication in retroperitoneal sarcoma survivors: Development and external validation of two dynamic nomograms

PURPOSE

The aim of this study was to create and validate dynamic nomograms to predict overall survival (OS) and disease-free survival (DFS) at different time points during follow-up in patients who had undergone resection of primary retroperitoneal sarcoma (RPS).

METHODS

Patients with primary RPS operated upon between 2002 and 2017 at four and six referral centres comprised the development and external validation cohorts, respectively. Landmark analysis and multivariable Cox models were used to develop dynamic nomograms. Variables were selected using two backward procedures based on the Akaike information criterion. The prediction window was fixed at 5 years. Nomogram performances were tested in terms of calibration and discrimination on the development and validation cohorts.

RESULTS

Development and validation cohorts totalled 1357 and 487 patients (OS analysis), and 1309 and 452 patients (DFS analysis), respectively. The final OS model included age, landmark time (T_LM), tumour grade, completeness of resection and occurrence of local/distant recurrence. The final DFS model included T_LM, histologic subtype, tumour size, tumour grade, multifocality and the interaction terms between T_LM and size, grade and multifocality. For OS, Harrell C indices were higher than 0.7 in both cohorts, indicating very good discriminative capability. For DFS, Harrell C indices were between 0.64 and 0.72 in the development cohort and 0.62 and 0.68 in the validation cohort. Calibration plots showed good agreement between predicted and observed outcomes.

CONCLUSION

Validated nomograms are available to predict the 5-year OS and DFS probability at different time points throughout the first 5 years of follow-up in RPS survivors.

[Retroperitoneal soft tissue sarcoma: role of radiotherapy]

BACKGROUND

Retroperitoneal soft tissue sarcomas (RPS) include tumors of mesenchymal origin with overall well-defined histological subtypes and heterogenic prognosis. For the first time with the publication of the STRASS study, which investigated the value of neoadjuvant radiotherapy in primary RPS, there is phase III evidence for the use of radiotherapy.

OBJECTIVE

The primary objective of the present article is to present the role of neoadjuvant radiotherapy in RPS since the publication of the STRASS study.

MATERIAL AND METHODS

We performed a non-systematic literature search. The results of retrospective and observational studies were compared to those of the STRASS study.

RESULTS

In the two of the largest analyses, the surveillance, epidemiology, and end results program (SEER) and the American National Cancer Database (NCDB), an improvement in overall survival due to radiotherapy in RPS could be shown. In contrast to these results, there was no significant improvement in 3‑year abdominal recurrence-free survival in the STRASS study. There was solely a trend to improved abdominal recurrence-free survival in initially unplanned subgroup analyses for patients with liposarcoma as well as low-grade sarcoma but not for leiomyosarcoma or high-grade sarcoma.

CONCLUSION

Thanks to international collaboration an academic randomized trial was even feasible in such a rare disease as RPS. The results of the STRASS study have relativized the potential benefit of radiotherapy in RPS. A longer follow-up especially regarding the role of radiotherapy in liposarcomas is desirable.

Multidisciplinary Management of Retroperitoneal Sarcoma: Diagnosis, Prognostic Factors and Treatment

Simple Summary

The management of retroperitoneal sarcomas can be challenging due to the variety of their presentation, histopathological types, and behaviours. This literature review provides a comprehensive and practical overview of the management of retroperitoneal sarcomas, focusing on diagnostic challenges, prognostic factors, multidisciplinary aspects of treatment and new research perspectives.

Abstract

Retroperitoneal sarcomas (RPS) are rare cancers whose management can be challenging due to various presentation patterns, multiple organ involvement, and a high local and distant recurrence rate. Histopathology and prognostic factors analysis are essential to predict the behaviour of the disease and plan the best therapeutic strategy. To date, surgery is still the main therapeutic option that guarantees a chance of cure from the primary disease. While chemotherapy and radiotherapy seem to be good options for controlling metastatic and recurrent irresectable disease, their role in the treatment of primary RPS remains unclear. This literature review aims to provide a comprehensive overview of the multidisciplinary aspects of RPS management in high-volume centres, summarising the diagnostic path, the prognostic factors, and the most suitable therapeutic options.

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.

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.