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.

Defining the role of neoadjuvant systemic therapy in high-risk retroperitoneal sarcoma: A multi-institutional study from the Transatlantic Australasian Retroperitoneal Sarcoma Working Group.

BACKGROUND: In patients with retroperitoneal sarcoma (RPS), the incidence of recurrence after surgery remains high. Novel treatment approaches are needed. This retrospective study evaluated patients with primary, high-risk RPS who received neoadjuvant systemic therapy followed by surgery to 1) determine the frequency and potential predictors of radiologic tumor responses and 2) assess clinical outcomes. METHODS: Clinicopathologic data were collected for eligible patients treated at 13 sarcoma referral centers from 2008 to 2018. Univariable and multivariable logistic models were performed to assess the association between clinical predictors and response. Overall survival (OS) and crude cumulative incidences of local recurrence and distant metastasis were compared. RESULTS: Data on 158 patients were analyzed. A median of 3 cycles of neoadjuvant systemic therapy (interquartile range, 2-4 cycles) were given. The regimens were mostly anthracycline based; however, there was significant heterogeneity. No patients demonstrated a complete response, 37 (23%) demonstrated a partial response (PR), 88 (56%) demonstrated stable disease, and 33 (21%) demonstrated progressive disease (PD) according to the Response Evaluation Criteria in Solid Tumors, version 1.1. Only a higher number of cycles given was positively associated with PR (P = .005). All patients underwent complete resection, regardless of the tumor response. Overall, patients whose tumors demonstrated PD before surgery showed markedly worse OS (P = .005). An indication of a better clinical outcome was seen in specific regimens given for grade 3 dedifferentiated liposarcoma and leiomyosarcoma. CONCLUSIONS: In patients with high-risk RPS, the response to neoadjuvant systemic therapy is fair overall. Disease progression on therapy may be used to predict survival after surgery. Subtype-specific regimens should be further validated.

Micrometastatic cancer cells in lymph nodes, bone marrow, and blood: Clinical significance and biologic implications.

Cancer metastasis may be regarded as a progressive process from its inception in the primary tumor microenvironment to distant sites by way of the lymphovascular system. Although this type of tumor dissemination often occurs in an orderly fashion via the sentinel lymph node (SLN), acting as a possible gateway to the regional lymph nodes, bone marrow, and peripheral blood and ultimately to distant metastatic sites, this is not a general rule as tumor cells may enter the blood and spread to distant sites, bypassing the SLN. Methods of detecting micrometastatic cancer cells in the SLN, bone marrow, and peripheral blood of patients have been established. Patients with cancer cells in their SLN, bone marrow, or peripheral blood have worse clinical outcomes than patients with no evidence of spread to these compartments. The presence of these cells also has important biologic implications for disease progression and the clinician's understanding of the process of cancer metastasis. Further characterization of these micrometastatic cancer cells at each stage and site of metastasis is needed to design novel selective therapies for a more "personalized" treatment.

Dedifferentiation within well-differentiated liposarcoma of the extremity or trunk: Implications for clinical management.

BACKGROUND: In extremity or trunk liposarcoma, the implications of a dedifferentiated (DD) component within a well-differentiated (WD) tumor are unclear. We evaluated outcomes after surgery and identified potential predictors of survival in these patients compared to those with an entirely WD tumor. METHODS: Retrospective data were collected for patients who underwent complete resection from 2009 to 2019. Cumulative incidences of local recurrence (LR) and distant metastasis (DM) were calculated, and overall survival (OS) was estimated. Associations between OS and clinicopathologic variables were evaluated by univariable models. RESULTS: A total of 210 patients with MDM2-verified tumors were studied, including 58 (27.6%) with DD. In primary disease, LR occurred only in DD and worse OS was observed versus WD (p < 0.001). In recurrent disease, the LR incidences were similar between WD and DD (p = 0.559); however, worse OS persisted in DD (p = 0.004). The incidence of DM was extremely low (3.8%) and limited to DD. Higher grade (p < 0.001) and DD size (p = 0.043), but not overall tumor size were associated with worse OS. CONCLUSIONS: In extremity or trunk liposarcoma, the presence of DD leads to significantly worse outcomes in both primary and recurrence diseases. Further study is needed to determine if these patients benefit from adjunct therapies (e.g., radiation).

The role of 18 F-FDG PET/CT in retroperitoneal sarcomas-A multicenter retrospective study.

BACKGROUND: The role of 18 F-fluorodeoxyglucose positron emission tomography/computed tomography (18 F-FDG PET/CT) in the evaluation of retroperitoneal sarcomas is poorly defined. We evaluated the correlation of maximum standardized uptake value (SUVmax) with pathologic tumor grade in the surgical specimen of primary retroperitoneal dedifferentiated liposarcoma (DDLPS) and leiomyosarcoma (LMS). METHODS: Patients with the above histological subtypes in three participating institutions with preoperative 18 F-FDG PET/CT scan and histopathological specimen available for review were included. The association between SUVmax and pathological grade was assessed. Correlation between SUVmax and relapse-free survival (RFS) and overall survival (OS) were also studied. RESULTS: Of the total 58 patients, final pathological subtype was DDLPS in 44 (75.9%) patients and LMS in 14 (24.1%) patients. The mean SUVmax was 8.7 with a median 7.1 (range, 2.2-33.9). The tumors were graded I, II, III in 6 (10.3%), 35 (60.3%), and 17 (29.3%) patients, respectively. There was an association of higher histological grade with higher SUVmax (rs = 0.40, p = .002). Increasing SUVmax was associated with worse RFS (p = .003) and OS (p = .003). CONCLUSION: There is a correlation between SUVmax and pathologic tumor grade; increasing SUVmax was associated with worse OS and RFS, providing a preoperative noninvasive surrogate marker of tumor grade and biological behavior.

Primary mesenteric sarcomas: Collaborative experience from the Trans-Atlantic Australasian Retroperitoneal Sarcoma Working Group (TARPSWG).

BACKGROUND: Primary mesenteric soft tissue sarcomas (STS) are rare and limited evidence is available to inform management. Surgical resection is challenging due to the proximity of vital structures and a need to preserve enteric function. OBJECTIVES: To determine the overall survival (OS) and recurrence-free survival (RFS) for patients undergoing primary resection for mesenteric STS. METHODS: The Trans-Atlantic Australasian Retroperitoneal Sarcoma Working Group (TARPSWG) is an intercontinental collaborative comprising specialist sarcoma centers. Data were collected retrospectively for all patients with mesenteric STS undergoing primary resection between 2000 and 2019. RESULTS: Fifty-six cases from 15 institutions were included. The spectrum of pathology was similar to the retroperitoneum, although of a higher grade. R0/R1 resection was achieved in 87%. Median OS was 56 months. OS was significantly shorter in higher-grade tumors (p = .018) and extensive resection (p < .001). No significant association between OS and resection margin or tumor size was detected. Rates of local recurrence (LR) and distant metastases (DM) at 5 years were 60% and 41%, respectively. Liver metastases were common (60%), reflecting portal drainage of the mesentery. CONCLUSION: Primary mesenteric sarcoma is rare, with a modest survival rate. LR and DM are frequent events. Liver metastases are common, highlighting the need for surveillance imaging.

Risk Factors for Wound Complications After Soft Tissue Sarcoma Resection.

ABSTRACT: Soft tissue sarcomas are a heterogenous group of malignant tumors that represent approximately 1% of adult malignancies. Although these tumors occur throughout the body, the majority involved the lower extremity. Management may involve amputation but more commonly often includes wide local resection by an oncologic surgeon and involvement of a plastic surgeon for reconstruction of larger and more complex defects. Postoperative wound complications are challenging for the surgeon and patient but also impact management of adjuvant chemotherapy and radiation therapy. To explore risk factors for wound complications, we reviewed our single-institution experience of lower-extremity soft tissue sarcomas from April 2009 to September 2016. We identified 127 patients for retrospective review and analysis. The proportion of patients with wound complications in the cohort was 43.3%. Most notably, compared with patients without wound complications, patients with wound complications had a higher proportion of immediate reconstruction (34.5% vs 15.3%; P = 0.05) and a marginally higher proportion who received neoadjuvant radiation (30.9% vs 16.7%; P = 0.06).

Historical perspectives and future directions in the surgical management of retroperitoneal sarcoma.

Retroperitoneal sarcomas (RPS) have fascinated and intrigued physicians both past and present. Operative mortality rates were historically very high and complete resection was not possible for the majority of patients until only the last 2 decades. More recently, changes to the surgical approach and clinical decision-making in RPS have improved patient outcomes. With select integration of nonsurgical therapies, continued RPS-specific research, and ongoing collaborative efforts among major referral centers, the future appears promising.

Imaging of liposarcomas for clinicians: Characteristic features and differential considerations.

Liposarcoma (LPS) is a malignancy of fat and one of the most common soft tissue sarcomas. There are three major subtypes of LPS: Well-differentiated / dedifferentiated, myxoid, and pleomorphic. We review the imaging features of LPS in the abdomen and extremities, describe features that help differentiate the subtypes, and provides alternative considerations for fat-containing lesions (many benign) that can mimic LPS.

The role of margins in extremity soft tissue sarcoma.

For extremity soft tissue sarcomas, limb salvage is now standard of care. The extent of surgical margins is balanced with functionality of the resected limb. Although negative margins are the goal, the necessary width is unclear. Additional considerations for margin adequacy include presence of anatomic barriers such as fascia and periosteum, proximity of critical structures, receipt of adjuvant and neoadjuvant therapies, and histologic subtype. Multidisciplinary team discussion is critical for treatment planning.

Phase 1 adaptive dose-finding study of neoadjuvant gemcitabine combined with radiation therapy for patients with high-risk extremity and trunk soft tissue sarcoma.

BACKGROUND: This study was performed to determine the maximum tolerated dose (MTD) of gemcitabine given concurrently with preoperative, fixed-dose external-beam radiation therapy (EBRT) for patients with resectable, high-risk extremity and trunk soft tissue sarcoma (STS). METHODS: Gemcitabine was administered on days 1, 8, 22, 29, 43, and 50 with EBRT (50 Gy in 25 fractions over 5 weeks). The gemcitabine MTD was determined with a toxicity severity weight method (TSWM) incorporating 6 toxicity types. The TSWM is a Bayesian procedure that choses each cohort's dose to have a posterior mean total toxicity burden closest to a predetermined clinician-defined target. Clinicopathologic and outcome data were also collected. RESULTS: Thirty-six patients completed the study. According to the TSWM, the gemcitabine MTD was 700 mg/m(2). At this dose level, 4 patients (24%) experienced grade 4 toxicity; no toxicity-related deaths occurred. All tumors were resected with microscopically negative margins. Pathologic responses of >90% tumor necrosis were achieved in 17 patients (47%); 14 (39%) had complete responses. With a median follow-up of 6.2 years, the 5-year locoregional recurrence-free survival, distant metastasis-free survival, and overall survival rates were 85%, 80%, and 86%, respectively. CONCLUSIONS: The TSWM combines data from qualitatively different toxicities and can be used to determine the MTD for a drug given as part of a multimodality treatment. Neoadjuvant gemcitabine plus radiation therapy is feasible and safe in patients with high-risk extremity and trunk STS. Major pathologic responses can be achieved, and after complete resection, long-term clinical outcomes are encouraging.

Follow-up of the soft tissue sarcoma patient.

Despite optimal treatment, patients with soft tissue sarcoma are at risk for recurrence and therefore appropriate surveillance is critical. At minimum, regularly scheduled clinical assessments and chest X-rays are necessary. Consensus guidelines are available; however, surveillance strategies must be personalized based on the risk for recurrence and inherent disease biology. Further research is needed on a number of issues, including the impact of surveillance on clinical outcome and the utility of molecular surveillance.

Contemporary imaging of soft tissue sarcomas.

Imaging plays an important role in the diagnosis, biopsy, staging, and follow-up of patients with soft tissue sarcomas. General principles of imaging diagnosis of soft-tissue sarcomas using radiography, ultrasound, CT, MRI, and PET/CT will be discussed, with emphasis on the role of location, internal fat and calcification, presence of myxoid stroma, and enhancement characteristics.

Contemporary Management of Retroperitoneal Soft Tissue Sarcomas.

Management of retroperitoneal soft tissue sarcomas (RP STS) can be very challenging. In contrast to the more common extremity STS, the two predominant histologic subtypes encountered in the retroperitoneum are well-differentiated/dedifferentiated liposarcoma and leiomyosarcoma. Surgery remains the mainstay of treatment for RP STS. Preoperative planning and anticipation of the need for resection of adjacent organs/structures are critical. The extent of surgery, including the role of compartmental resection, is still controversial. Radiation therapy may be an important adjunct to surgery to provide locoregional disease control; this is currently being evaluated in the preoperative setting in the EORTC STRASS trial. Systemic therapy, tailored to the specific histologic subtype, may also be of benefit for the management of RP STS. Further investigation of novel therapies (e.g., targeted therapies, immunotherapy) is needed. Overall, multi-institutional collaboration is important moving forward, to continue to better understand and optimize management of this disease.

Locoregional disease patterns in well-differentiated and dedifferentiated retroperitoneal liposarcoma: implications for the extent of resection?

BACKGROUND: Well-differentiated (WD)/dedifferentiated (DD) liposarcoma is the most common soft tissue sarcoma of the retroperitoneum. The frequency of distant metastasis is low and the major burden of disease is locoregional. We sought to define the patterns of locoregional disease to help guide surgical decision making. METHODS: Data were collected from 247 patients with de novo or recurrent tumors treated at our institution from 1993 to early 2012. The number and location of tumors at both initial presentation and subsequent locoregional recurrence were determined by combined analysis of operative dictations and radiologic imaging. RESULTS: Thirty-four percent of patients had multifocal locoregional disease (two or more tumors) at initial presentation to our institution, including 9 % who had tumors at synchronous remote retroperitoneal sites. The impact of multifocal disease on overall survival was dependent on histologic subtype (WD vs. DD) and disease presentation (de novo vs. recurrence) at the time of resection. Among patients with initial unifocal disease, 57 % progressed to multifocal locoregional disease with subsequent recurrence, including 11 % with new tumors outside of the original resection field. No clinicopathologic or treatment-related variable, including the type or extent of resection, was predictive of either multifocal or 'outside field' progression. CONCLUSIONS: Multifocal disease is common in patients with WD/DD retroperitoneal liposarcoma, and tumors can also develop at remote, locoregional sites. Surgical resection remains the primary method of locoregional control in this disease; however, the aggressiveness of resection should be individualized, with consideration of both tumor and patient-related factors.

Diffuse intra-abdominal sarcomatosis in myxoid pleomorphic liposarcoma.

We present a case of an extremely rare type of soft-tissue sarcoma with an atypical clinical presentation. The patient, a female in her 20s with Li Fraumeni syndrome, had prior surgery for a large intra-abdominal tumour that was given the diagnosis of malignant myxoid spindle cell neoplasm. Her recurrence manifested as diffuse intra-abdominal sarcomatosis for which she ultimately underwent subtotal debulking with palliative intent. Final pathology rendered the diagnosis of myxoid pleomorphic liposarcoma, a newly described entity, distinct from the more common liposarcoma subtypes. The optimal treatment for this typically aggressive disease is currently unknown; until that is better defined, management should be carried out by sarcoma specialists.