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Opinion Statement: Leiomyosarcoma (LMS) is one of the more common subtypes of soft tissue sarcomas (STS), accounting for about 20% of cases. Differences in anatomical location, risk of recurrence and histomorphological variants contribute to the substantial clinical heterogeneity in survival outcomes and therapy responses observed in patients. There is therefore a need to move away from the current one-size-fits-all treatment approach towards a personalised strategy tailored for individual patients. Over the past decade, tissue profiling studies have revealed key genomic features and an additional layer of molecular heterogeneity among patients, with potential utility for optimal risk stratification and biomarker-matched therapies. Furthermore, recent studies investigating intratumour heterogeneity and tumour evolution patterns in LMS suggest some key features that may need to be taken into consideration when designing treatment strategies and clinical trials. Moving forward, national and international collaborative efforts to aggregate expertise, data, resources and tools are needed to achieve a step change in improving patient survival outcomes in this disease of unmet need., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Retroperitoneal sarcomas are tumours with a poor prognosis. Upfront characterisation of the tumour is difficult, and under-grading is common. Radiomics has the potential to non-invasively characterise the so-called radiological phenotype of tumours. We aimed to develop and independently validate a CT-based radiomics classification model for the prediction of histological type and grade in retroperitoneal leiomyosarcoma and liposarcoma., Methods: A retrospective discovery cohort was collated at our centre (Royal Marsden Hospital, London, UK) and an independent validation cohort comprising patients recruited in the phase 3 STRASS study of neoadjuvant radiotherapy in retroperitoneal sarcoma. Patients aged older than 18 years with confirmed primary leiomyosarcoma or liposarcoma proceeding to surgical resection with available contrast-enhanced CT scans were included. Using the discovery dataset, a CT-based radiomics workflow was developed, including manual delineation, sub-segmentation, feature extraction, and predictive model building. Separate probabilistic classifiers for the prediction of histological type and low versus intermediate or high grade tumour types were built and tested. Independent validation was then performed. The primary objective of the study was to develop radiomic classification models for the prediction of retroperitoneal leiomyosarcoma and liposarcoma type and histological grade., Findings: 170 patients recruited between Oct 30, 2016, and Dec 23, 2020, were eligible in the discovery cohort and 89 patients recruited between Jan 18, 2012, and April 10, 2017, were eligible in the validation cohort. In the discovery cohort, the median age was 63 years (range 27-89), with 83 (49%) female and 87 (51%) male patients. In the validation cohort, median age was 59 years (range 33-77), with 46 (52%) female and 43 (48%) male patients. The highest performing model for the prediction of histological type had an area under the receiver operator curve (AUROC) of 0·928 on validation, based on a feature set of radiomics and approximate radiomic volume fraction. The highest performing model for the prediction of histological grade had an AUROC of 0·882 on validation, based on a radiomics feature set., Interpretation: Our validated radiomics model can predict the histological type and grade of retroperitoneal sarcomas with excellent performance. This could have important implications for improving diagnosis and risk stratification in retroperitoneal sarcomas., Funding: Wellcome Trust, European Organisation for Research and Treatment of Cancer-Soft Tissue and Bone Sarcoma Group, the National Institutes for Health, and the National Institute for Health and Care Research Biomedical Research Centre at The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research., Competing Interests: Declaration of interests AA reports funding from the Wellcome Trust paid to their institution. MRO, SD, and CM report funding paid to their institutions from the National Institute for Health and Care Research Biomedical Research Centre at The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, London. MRO reports funding from the Royal Marsden Cancer Charity to their institution. SD reports funding to their institution from Cancer Research UK. RH declares a previous role as the President of the Connective Tissue Oncology Society (in 2021). AG reports grants from PharmaMar and Nanobiotic; consulting fees from Novartis, Pfizer, Bayer, Lilly, PharmaMar, SpringWorks, and Boehringer Ingelheim; and honoraria from Deciphera. CPR reports royalties from UpTo Date. DVG reports grants from Elekta, IntraOp, and Orfit to their institution; consulting fees from Sanofi, Takeda, Novartis, and Merck; payment or honoraria from Elekta for lectures and support for attending meetings or travel; payment from Sanofi for expert testimony; and also declares a role in the Belgian College of Oncology and a research partnership with Elekta, Siemens, IntraOp and, MIM software, and a commercial partnership with Orfit, VisionRT, Philips, and Precisionxray. CLP reports payment from AstraZeneca to their institution for lectures; support for attending meetings and travel by Janseen and Ose Immunotherapeutics; and participation on advisory boards for AstraZeneca, Bristol Myers Squibbs and Varian. RJ reports grants from MSD and GSK and consulting fees from Adaptimmune, Astex, Athenex, Bayer, Boehringer Ingelheim, Blueprint, Clinigen, Eisai, Epizyme, Daichii, Deciphera, Immunedesign, Immunicum, Karma Oncology, Lilly, Merck, Mundipharma, PharmaMar, SpringWorks, Synox, Tracon, and UpTo Date. CM reports funding from European Organisation for Research and Treatment of Cancer-Soft Tissue and Bone Sarcoma Group to their institution; payment or honoraria from TeleMedicine Clinic academy and GE Healthcare; and support for meetings from International Cancer Imaging Society. CM also declares a role as trustee of the British Institution of Radiology and is a Fellow of the International Cancer Imaging Society. All other authors declare no competing interests., (Copyright © 2023 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 license. Published by Elsevier Ltd.. All rights reserved.)

Soft tissue sarcomas (STS) are rare and diverse mesenchymal cancers with limited treatment options. Here we undertake comprehensive proteomic profiling of tumour specimens from 321 STS patients representing 11 histological subtypes. Within leiomyosarcomas, we identify three proteomic subtypes with distinct myogenesis and immune features, anatomical site distribution and survival outcomes. Characterisation of undifferentiated pleomorphic sarcomas and dedifferentiated liposarcomas with low infiltrating CD3 + T-lymphocyte levels nominates the complement cascade as a candidate immunotherapeutic target. Comparative analysis of proteomic and transcriptomic profiles highlights the proteomic-specific features for optimal risk stratification in angiosarcomas. Finally, we define functional signatures termed Sarcoma Proteomic Modules which transcend histological subtype classification and show that a vesicle transport protein signature is an independent prognostic factor for distant metastasis. Our study highlights the utility of proteomics for identifying molecular subgroups with implications for risk stratification and therapy selection and provides a rich resource for future sarcoma research., (© 2023. The Author(s).)

Leiomyosarcoma (LMS) is a soft tissue sarcoma of smooth muscle origin that can arise in multiple anatomical sites and is broadly classified as extra-uterine LMS or uterine LMS. There is substantial interpatient heterogeneity within this histological subtype, and despite multi-modal therapy, clinical management remains challenging with poor patient prognosis and few new therapies available. Here we discuss the current treatment landscape of LMS in both the localised and advanced disease setting. We further describe the latest advances in our evolving understanding of the genetics and biology of this group of heterogeneous diseases and summarise the key studies delineating the mechanisms of acquired and intrinsic chemotherapy resistance in this histological subtype. We conclude by providing a perspective on how novel targeted agents such as PARP inhibitors may usher in a new paradigm of biomarker-driven therapies that will ultimately impact the outcomes of patients with LMS., Competing Interests: Conflict of interest statement RLJ declares the receipt of grants and research support from MSD and GSK, as well as receipt of consultation fees from Adaptimmune, Astex, Athenex, Bayer, Boehringer Ingelheim, Blueprint, Clinigen, Eisai, Epizyme, Daichii, Deciphera, Immunedesign, Immunicum, Karma Oncology, Lilly, Merck, Mundipharma, Pharmamar, Springworks, SynOx, Tracon, and Upto Date. All other authors have no conflicts of interest to declare., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Primary leiomyosarcoma (LMS) of the gastrointestinal (GI) tract is rare. Limited literature exists regarding the clinical characteristics and outcome for patients with localised and metastatic disease., Methods: A retrospective chart review was performed for patients greater than 18 years of age diagnosed with GI LMS at The Royal Marsden Hospital between 1 January 2000-1 May 2020. Descriptive statistics were performed. Patients were censored at data cut-off date of 27 June 2020., Results: Forty-six patients with a median age at diagnosis of 54 years (range 25-85) were identified. Fifteen percent (n = 7) of patients previously received abdominal radiation for an unrelated cancer. All patients with localised disease (n = 36) had resection with oncological margins. For patients who underwent potentially curative surgery, median recurrence-free survival (mRFS) was 13 months (0.4-183 months), and half of these patients (n = 18) developed recurrent disease post resection (distant n = 16, local n = 2). Median overall survival (mOS) was 27 months for patients with distant recurrence. Twenty-one percent (n = 10) of patients presented with synchronous metastatic disease and their mOS was 19 months. Median progression-free survival (mPFS) for patients treated with conventional chemotherapy ranged from 2.0 to 8.0 months., Conclusion: The risk of recurrence is significant, and recurrence-free survival was short even with complete oncologic resection. The relationship of prior abdominal radiotherapy to the development of GI LMS warrants further investigation. Outcomes with systemic therapy for metastatic disease were poor and there is a need for the development of more effective systemic therapies., Competing Interests: Declaration of competing interest RLJ is the recipient of grants/research support from MSD, GSK. AJH and MJS are the recipient of research support from Amgen. RLJ is the recipient of consultation fees from Adaptimmune, Athenex, Blueprint, Clinigen, Eisai, Epizyme, Daichii, Deciphera, Immunedesign, Lilly, Merck, Pharmamar, UptoDate. MJFS has been an advisory board member for Amgen. All other authors have no conflicts of interest to declare., (Crown Copyright © 2021. Published by Elsevier Ltd. All rights reserved.)

Soft tissue sarcomas (STS) are a group of rare and heterogeneous cancers. While large-scale genomic and epigenomic profiling of STS have been undertaken, proteomic analysis has thus far been limited. Here we utilise sequential window acquisition of all theoretical fragment ion spectra mass spectrometry (SWATH-MS) for proteomic profiling of formalin fixed paraffin embedded (FFPE) specimens from a cohort of STS patients (n = 36) across four histological subtypes (leiomyosarcoma, synovial sarcoma, undifferentiated pleomorphic sarcoma and dedifferentiated liposarcoma). We quantified 2951 proteins across all cases and show that there is a significant enrichment of gene sets associated with smooth muscle contraction in leiomyosarcoma, RNA splicing regulation in synovial sarcoma and leukocyte activation in undifferentiated pleomorphic sarcoma. We further identified a subgroup of STS cases that have a distinct expression profile in a panel of proteins, with worse survival outcomes when compared to the rest of the cohort. Our study highlights the value of comprehensive proteomic characterisation as a means to identify histotype-specific STS profiles that describe key biological pathways of clinical and therapeutic relevance; as well as for discovering new prognostic biomarkers in this group of rare and difficult-to-treat diseases., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Initial grading of retroperitoneal leiomyosarcoma (LMS) is performed by core biopsy (CB) however, discrepancy between grade of tumour at initial CB and surgical excision is recognised, raising concerns about the accuracy of CB for directing neoadjuvant therapy. The histological grading system used for staging LMS consists of 3 components: tumour differentiation, mitotic index and proportion of necrosis. We postulate that assessment of necrosis by histopathology alone is inadequate, resulting in under-grading of LMS. We propose and assess a combined grading system that incorporates CT scan findings into pre-surgical grading., Methods: Retrospective, blinded review of CT, CB histology and final surgical histology of patients with retroperitoneal LMS was undertaken. A modified grading system, CT H-Grade, was derived by replacing the CB necrosis score with a CT-derived necrosis score. The sensitivity and specificity of CT H-Grade, the standard histopathology scoring, H-grade were compared. Inter-observer variability in assessment of CT necrosis was also assessed., Results: 53 patients fulfilled criteria for inclusion. CT was more sensitive at detection of necrosis than CB histology alone with sensitivity of 100% vs 53%. The use of CT HGrade resulted in increased detection of high-grade tumours with CT H-grade having sensitivities of 80% and 35% for Grade 2 and 3 tumours respectively vs 53% and 15% with H-Grade. Assessment of reader agreement demonstrated Kappa scores of 0.8., Conclusion: Histology from CB under-grades LMS due to undersampling of tumour necrosis. CT is more sensitive in assessing necrosis and its incorporation into a modified CT-histopathology grading system ( CT H-Grade) improves accuracy of grading with significant implications for patient management., Competing Interests: Declaration of competing interest The authors do not have any conflicts of interest to declare., (Copyright © 2019. Published by Elsevier Ltd.)

The characterisation and clinical relevance of tumour-infiltrating lymphocytes (TILs) in leiomyosarcoma (LMS), a subtype of soft tissue sarcoma that exhibits histological heterogeneity, is not established. The use of tissue microarrays (TMA) in studies that profile TIL burden is attractive but given the potential for intra-tumoural heterogeneity to introduce sampling errors, the adequacy of this approach is undetermined. In this study, we assessed the histological inter- and intra-tumoural heterogeneity in TIL burden within a retrospective cohort of primary LMS specimens. Using a virtual TMA approach, we also analysed the optimal number of TMA cores required to provide an accurate representation of TIL burden in a full tissue section. We establish that LMS have generally low and spatially homogenous TIL burdens, although a small proportion exhibit higher levels and more heterogeneous distribution of TILs. We show that a conventional and practical number (e.g. ≤3) of TMA cores is adequate for correct ordinal categorisation of tumours with high or low TIL burden, but that many more cores (≥11) are required to accurately estimate absolute TIL numbers. Our findings provide a benchmark for the design of future studies aiming to define the clinical relevance of the immune microenvironments of LMS and other sarcoma subtypes.

We highlight a rare variant pattern of low-grade endometrial stromal sarcoma showing extensive collagenous rosette formation, closely mimicking low-grade fibromyxoid sarcoma. Additionally, this neoplasm showed diffuse and strong expression of muscle markers, favoring an initial diagnosis of leiomyosarcoma. Reverse transcription-polymerase chain reaction showed the presence of JAZF1-SUZ12 fusion transcripts, and this highlights the broad morphologic and immunophenotypic spectrum of endometrial stromal sarcoma.

The grading of soft tissue sarcomas is one of the most important prognostic factors and determines patient management. Although grading of most adult-type soft tissue sarcomas on biopsies correlates highly with the final grading on the excision specimen, it appears less reliable for tumors of smooth muscle. We assessed the pathologic findings for smooth muscle neoplasms diagnosed by core biopsy at our tertiary sarcoma center, and compared them with those in the subsequent excision specimens. A total of 100 patients with leiomyosarcoma first diagnosed on core biopsy and with a subsequent excision were identified and the accuracy of the biopsy grade determined by comparison with the excision grade. Differences in other salient histologic parameters were also noted. A grade difference between biopsy and excision specimens of leiomyosarcomas was found in 68% of cases, with all these cases showing an increase in grade from biopsy to excision specimen. Of the 3 parameters used for grading using the French Federation of Cancer Centers Sarcoma Group Grading System (FNCLCC), necrosis was the score that most commonly differed between biopsy and excision specimen (55%), closely followed by the mitotic count (51%). The grading of soft tissue smooth muscle tumor biopsies has a lower accuracy compared with other adult soft tissue sarcomas and should therefore be taken with caution, particularly as this may be an underrepresentation of the true tumor grade.

Background: Soft tissue sarcomas are a group of neoplasms with differentiation towards mesenchymal tissue, many of which are aggressive and chemotherapy resistant. Histology and immunoprofiles often overlap with neoplasms of other lineages, and establishing an accurate histopathological diagnosis is crucial for correct management, and therapeutic stratification. The endosialin cell surface glycoprotein is predominantly expressed by stromal fibroblasts and pericytes in epithelial neoplasms; however, tumour cell expression has been reported in small series of sarcomas., Methods: We assessed endosialin expression by immunohistochemistry in a large set of 514 human soft tissue sarcomas., Results: Tumour cell endosialin expression was seen in 89% of undifferentiated pleomorphic sarcomas (104/117), 77% adult fibrosarcomas/spindle cell sarcomas (20/26), 62% synovial sarcomas (37/60), 51% leiomyosarcomas (94/185) and 31% rhabdomyosarcomas (39/126)., Conclusions: Endosialin immunohistochemistry has potential to distinguish undifferentiated and poorly differentiated sarcomas from other poorly differentiated, non-mesenchymal neoplasms. A Phase II trial randomising patients with advanced sarcomas to receive chemotherapy with/without an endosialin therapeutic antibody has recently completed enrolment. Endosialin expression could be used to select patients for such clinical trials. Based on our results, patients with undifferentiated pleomorphic sarcoma may be particularly suitable for such a therapeutic approach.

Aim: To evaluate the cross-sectional radiological appearances and to review the clinical presentation and outcome of patients with leiomyosarcomas of the inferior vena cava (IVC LMS). These are rare aggressive tumours that present late with non-specific symptoms and have a poor prognosis., Materials and Methods: From January 2002 to December 2008, the radiological images of 23 sequential patients with pathologically proven IVC LMS were independently reviewed by two experienced radiologists. The clinical presentation, treatment including surgical details, and outcome were recorded., Results: There were 19 females and four males with a mean age of 53 years. CT typically demonstrated a large, lobulate, non-calcified heterogeneous mass with peripheral enhancement. T1-weighted magnetic resonance imaging (MRI) images demonstrated a mass with a low signal intensity and T2-weighted MRI images demonstrated a mass with a high signal intensity. Clinical presentation included leg oedema, back and abdominal pain with almost 50% of patients presenting with metastases. Eleven patients underwent ablative surgery. The mean survival time of all patients in the study was 34 months and that of the 11 post-surgical patients was 56 months., Conclusion: There are a variety of diagnostic features on both computed tomography (CT) and MRI which aid the diagnosis of this unusual vascular neoplasm. CT is vital in determining the location of the tumour within the IVC and MRI accurately depicts its extent and the potential for surgical resectability, which offers the only chance of survival., (Copyright © 2010 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Background: Leiomyosarcomas of the urinary bladder (LMS-UB) are rare, usually aggressive neoplasms. Owing to their rarity, only a limited number of cases with clinical follow-up information have been published. There is no current consensus on LMS-UB grading, and it is unknown whether the widely accepted Fédération Nationale des Centres de Lutte Contre le Cancer (FNCLCC) and National Cancer Institute (NCI) grading systems of soft-tissue sarcomas are applicable to LMS-UB., Methods: The authors studied 34 well-characterised LMS-UB and compared the prognostic power of the FNCLCC and NCI systems with that of one published grading scheme for LMS-UB (Mayo). All available slides from 34 LMS-UB were retrieved and evaluated with regards to degree of differentiation, mitotic rate/10 high-powered fields (HPF), and % necrosis. Cases were graded using published criteria for the FNCLCC, NCI and Mayo schemes. Follow-up information was obtained., Results: The tumours occurred in 17 females and 17 males, ranging from 31 to 91 years (median 65), and measured 2-12 cm in size. One tumour was well differentiated, 17 tumours were moderately differentiated, and 16 tumours were poorly differentiated. Mitotic rates ranged from 1 to >30/10 HPF (median 12/10 HPF), and tumours showed 0-60% necrosis (median 25%). FNCLCC grades were 1 (3), 2 (12) and 3 (19). NCI grades were 1 (2), 2 (11) and 3 (21). Mayo grades were low (7) and high (27). FNCLCC and NCI grades were identical in 23/34 cases (68%). Four cases were FNCLCC/NCI grade 2 or 3 and Mayo low-grade. Clinical follow-up was available for 25 of 34 patients (74%). Clinical follow-up of > or =12 months was available for 17 of these 25 cases (68%) with a median follow-up duration of 52 months (range 12-120 months). Adverse outcome was seen in nine of these 17 patients (53%). Seven of the eight cases (88%) with a clinical follow-up duration of <12 months died of their disease. Overall, adverse outcome was documented in 16 of 25 (64%) cases. Metastatic disease was seen in 13 of 25 (52%) cases, with the lungs being the most common site of metastasis (62%). Adverse outcome was noted in 15 of 23 (65%) of FNCLCC grade 2 or 3 LMS-UB, as compared with zero of two (0%) FNCLCC grade 1 tumours (p=0.15), in 15 of 23 (65%) NCI grade 2 or 3 LMS-UB, versus zero of two (0%) NCI grade 1 sarcomas (p=0.17) and in 13 of 20 (65%) Mayo high grade LMS-UB, as opposed to two of five (40%) low-grade lesions (all results not statistically significant)., Conclusions: The authors conclude that LMS-UB occurs in older adults of either sex and is characterised by aggressive behaviour, with adverse outcome in >60% of cases. Certain advantages of the FNCLCC system may support its more widespread adoption for future studies.

Although soft-tissue masses are common, sarcomas are rare malignant neoplasms showing variable mesenchymal differentiation and can occur at any anatomical site. Limb soft-tissue sarcomas (STS) are rare, but often lethal tumours. Although there are scores of historical pathological subtypes, this article will deal with the commonest: liposarcoma, leiomyosarcoma (LMS), undifferentiated pleomorphic sarcoma (UPS), synovial sarcoma, myxofibrosarcoma, malignant peripheral nerve sheath tumour (MPNST), epithelioid sarcoma, alveolar rhabdosarcoma, angiosarcoma and radiation-induced sarcoma (RIS). Following a review of >4,000 adult patients with limb sarcoma from our specialist soft-tissue tumour database, we summarise the literature and their imaging findings, with emphasis on radiological hallmarks that can aide in diagnosis and management. Increased awareness of sarcoma when challenged with a new mass in the extremity can ensure timely and appropriate treatment. [ABSTRACT FROM AUTHOR]