Comprehensive Molecular Characterization of a Large Series of Calcified Chondroid Mesenchymal Neoplasms Widening Their Morphologic Spectrum.

Recently, FN1 fusions to receptor tyrosine kinase genes have been identified in soft tissue tumors with calcified chondroid matrix named calcifying chondroid mesenchymal neoplasms (CCMNs). We collected 33 cases of CCMN from the French network for soft tissue and bone tumors. We performed whole-exome RNA sequencing, expression analysis, and genome-wide DNA methylation profiling in 33, 30, and 20 cases of CCMN compared with a control group of tumors, including noncalcified tenosynovial giant cell tumor (TGCT). Among them, 15 cases showed morphologic overlap with soft tissue chondroma, 8 cases with tophaceous pseudogout, and 10 cases with chondroid TGCT. RNA-sequencing revealed a fusion of FN1 in 76% of cases (25/33) with different 5' partners, including most frequently FGFR2 (14 cases), TEK or FGFR1. Among CCMN associated with FGFR1 fusions, 2 cases had overexpression of FGF23 without tumor-induced osteomalacia. Four CCMN had PDGFRA::USP8 fusions; 3 of which had histologic features of TGCT and were located in the hip, foot, and temporomandibular joint (TMJ). All cases with FN1::TEK fusion were located at TMJ and had histologic features of TGCT with or without chondroid matrix. They formed a distinct cluster on unsupervised clustering analyses based on whole transcriptome and genome-wide methylome data. Our study confirms the high prevalence of FN1 fusions in CCMN. In addition, through transcriptome and methylome analyses, we have identified a novel subgroup of tumors located at the TMJ, exhibiting TGCT-like features and FN1::TEK fusions.

Alveolar soft part sarcomas in young patients: The French national NETSARC+ network experience.

BACKGROUND AND AIMS: Alveolar soft part sarcoma (ASPS) is an ultra-rare chemo-resistant sarcoma in children, occurring preferentially in young adults. We aimed to describe and compare its clinical presentation and behaviour in children and young adults to determine whether the same therapeutic strategy should be addressed for both populations. METHODS: National retrospective multicentre study of children (0-18 years) vs. young adults (19-30 years) included in the "ConticaBase" sarcoma database, treated for ASPS between 2010 and 2019 with pathology reviewed via the NETSARC + network. RESULTS: Overall, 45 patients were identified, 19 children (42%) and 26 young adults (58%). All ASPS diagnoses were confirmed with TFE3 rearrangement by immunohistochemistry or FISH. All clinical characteristics were balanced between both populations with frequent metastases at diagnosis (8/19 vs. 10/26). The therapeutic strategy was based on surgery (17/19 vs. 21/26), radiotherapy (8/19 vs. 12/26) ± systemic treatment (8/19 vs. 9/26). In patients with initially localized disease, metastatic relapse occurred only in adults (8/16), whereas metastatic progression was present in both metastatic groups (5/8 vs. 8/10). After a median follow-up of 5.2 years (range, 0.2-12.2), 5-year EFS was 74% [95%CI, 56-96] vs. 47% [30-74] (p = 0.071) respectively, and 5-year OS was 95% [85-100] vs. 85% [70-100] (p = 0.84). For localized tumours, 5-year MFS was 100% [100-100] vs. 60% [39-91] (p = 0.005). The 5-year OS of all patients with metastasis at diagnosis was 80.2% (62.2%-100%). CONCLUSIONS: ASPS appears to have the overall same clinical characteristics, but a more aggressive behaviour in young adults than in children. However, despite frequent metastases at diagnosis, long-term survival is high in both groups. Overall, the same therapeutic strategies may be considered for both populations.

Improved Metastatic-Free Survival after Systematic Re-Excision Following Complete Macroscopic Unplanned Excision of Limb or Trunk Soft Tissue Sarcoma.

BACKGROUND: Whether re-excision (RE) of a soft tissue sarcoma (STS) of limb or trunk should be systematized as adjuvant care and if it would improve metastatic free survival (MFS) are still debated. The impact of resection margins after unplanned macroscopically complete excision (UE) performed out of a NETSARC reference center or after second resection was further investigated. METHODS: This large nationwide series used data from patients having experienced UE outside of a reference center from 2010 to 2019, collected in a French nationwide exhaustive prospective cohort NETSARC. Patient characteristics and survival distributions in patients reexcised (RE) or not (No-RE) are reported. Multivariate Cox proportional hazard model was conducted to adjust for classical prognosis factors. Subgroup analysis were performed to identify which patients may benefit from RE. RESULTS: Out of 2371 patients with UE for STS performed outside NETSARC reference centers, 1692 patients were not reviewed by multidisciplinary board before treatment decision and had a second operation documented. Among them, 913 patients experienced re-excision, and 779 were not re-excised. Characteristics were significantly different regarding patient age, tumor site, size, depth, grade and histotype in patients re-excised (RE) or not (No-RE). In univariate analysis, final R0 margins are associated with a better MFS, patients with R1 margins documented at first surgery had a better MFS as compared to patients with first R0 resection. The study identified RE as an independent favorable factor for MFS (HR 0.7, 95% CI 0.53-0.93; p = 0.013). All subgroups except older patients (>70 years) and patients with large tumors (>10 cm) had superior MFS with RE. CONCLUSIONS: RE might be considered in patients with STS of limb or trunk, with UE with macroscopic complete resection performed out of a reference center, and also in originally defined R0 margin resections, to improve LRFS and MFS. Systematic RE should not be advocated for patients older than 70 years, or with tumors greater than 10 cm.

Evolution of Patterns of Care and Outcomes in the Real-Life Setting for Patients with Metastatic GIST Treated in Three French Expert Centers over Three Decades.

Gastrointestinal stromal tumors (GIST) are rare mesenchymal tumors characterized by KIT or PDGFRA mutations. Over three decades, significant changes in drug discovery and loco-regional (LR) procedures have impacted treatment strategies. We assessed the evolution of treatment strategies for metastatic GIST patients treated in the three national coordinating centers of NetSarc, the French network of sarcoma referral centers endorsed by the National Institute of Cancers, from 1990 to 2018. The primary objective was to describe the clinical and biological profiles as well as the treatment modalities of patients with metastatic GIST in a real-life setting, including access to clinical trials and LR procedures in the metastatic setting. Secondary objectives were to assess (1) patients' outcome in terms of time to next treatment (TNT) for each line of systemic treatment, (2) patients' overall survival (OS), (3) evolution of patients' treatment modalities and OS according to treatment access: <2002 (pre-imatinib approval), 2002-2006 (pre-sunitinib approval), 2006-2014 (pre-regorafenib approval), post 2014, and (4) the impact of clinical trials and LR procedures on TNT and OS in the metastatic setting. 1038 patients with a diagnosis of GIST made in one of the three participating centers between 1990 and 2018 were included in the national prospective database. Among them, 492 patients presented metastasis, either synchronous or metachronous. The median number of therapy lines in the metastatic setting was 3 (range 0-15). More than half of the patients (55%) participated in a clinical trial during the course of their metastatic disease and half (51%) underwent additional LR procedures on metastatic sites. The median OS in the metastatic setting was 83.4 months (95%CI [72.7; 97.9]). The median TNT was 26.7 months (95%CI [23.4; 32.3]) in first-line, 10.2 months (95%CI [8.6; 11.8]) in second line, 6.7 months (95%CI [5.3; 8.5]) in third line, and 5.5 months (95%CI [4.3; 6.7]) in fourth line, respectively. There was no statistical difference in OS in the metastatic setting between the four therapeutic periods (log rank, p = 0.18). In multivariate analysis, age, AFIP Miettinen classification, mutational status, surgery of the primary tumor, participation in a clinical trial in the first line and LR procedure to metastatic sites were associated with longer TNT in the first line, whereas age, mitotic index, mutational status, surgery of the primary tumor and LR procedure to metastatic sites were associated with longer OS. This real-life study advocates for early reference of metastatic GIST patients to expert centers to orchestrate the best access to future innovative clinical trials together with LR strategies and further improve GIST patients' survival.

A TLR4 Agonist Induces Osteosarcoma Regression by Inducing an Antitumor Immune Response and Reprogramming M2 Macrophages to M1 Macrophages.

Osteosarcoma (OsA) has limited treatment options and stagnant 5-year survival rates. Its immune microenvironment is characterized by a predominance of tumor-associated macrophages (TAMs), whose role in OsA progression remain unclear. Nevertheless, immunotherapies aiming to modulate macrophages activation and polarization could be of interest for OsA treatment. In this study, the antitumor effect of a liposome-encapsulated chemically detoxified lipopolysaccharide (Lipo-MP-LPS) was evaluated as a therapeutic approach for OsA. Lipo-MP-LPS is a toll-like receptor 4 (TLR4) agonist sufficiently safe and soluble to be IV administered at effective doses. Lipo-MP-LPS exhibited a significant antitumor response, with tumor regression in 50% of treated animals and delayed tumor progression in the remaining 50%. The agent inhibited tumor growth by 75%, surpassing the efficacy of other immunotherapies tested in OsA. Lipo-MP-LPS modulated OsA's immune microenvironment by favoring the transition of M2 macrophages to M1 phenotype, creating a proinflammatory milieu and facilitating T-cell recruitment and antitumor immune response. Overall, the study demonstrates the potent antitumor effect of Lipo-MP-LPS as monotherapy in an OsA immunocompetent model. Reprogramming macrophages and altering the immune microenvironment likely contribute to the observed tumor control. These findings support the concept of immunomodulatory approaches for the treatment of highly resistant tumors like OsA.

Comprehensive Immune Profiling Unveils a Subset of Leiomyosarcoma with "Hot" Tumor Immune Microenvironment.

Purpose: To investigate the immune biomarker in Leiomyosarcoma (LMS), which is rare and recognized as an immune cold cancer showing a poor response rate (<10%) to immune checkpoint inhibitors (ICIs). However, durable response and clinical benefit to ICIs has been observed in a few cases of LMS, including, but not only, LMS with tertiary lymphoid structure (TLS) structures. Patients and methods: We used comprehensive transcriptomic profiling and a deconvolution method extracted from RNA-sequencing gene expression data in two independent LMS cohorts, the International Cancer Genome Consortium (ICGC, N = 146) and The Cancer Genome Atlas (TCGA, N = 75), to explore tumor immune microenvironment (TIME) in LMS. Results: Unsupervised clustering analysis using the previously validated two methods, 90-gene signature and Cell-type Identification by Estimating Relative Subsets of RNA Transcripts (CIBERSORT), identified immune hot (I-H) and immune high (I-Hi) LMS, respectively, in the ICGC cohort. Similarly, immune active groups (T-H, T-Hi) were identified in the TCGA cohort using these two methods. These immune active ("hot") clusters were significantly associated, but not completely overlapping, with several validated immune signatures such as sarcoma immune class (SIC) classification and TLS score, T cell inflamed signature (TIS) score, immune infiltration score (IIS), and macrophage score (M1/M2), with more patients identified by our clustering as potentially immune hot. Conclusions: Comprehensive immune profiling revealed a subset of LMS with a distinct active ("hot") TIME, consistently associated with several validated immune signatures in other cancers. This suggests that the methodologies that we used in this study warrant further validation and development, which can potentially help refine our current immune biomarkers to select the right LMS patients for ICIs in clinical trials.

Neurotrophic tropomyosin receptor kinase (NTRK) fusion positive tumors: a historical cohort analysis.

BACKGROUND: NTRK gene fusions have been identified in various tumors; some requiring aggressive therapy and sometimes new TRK inhibitors (TRKi). We aimed to describe a national, unselected, retrospective, multicenter cohort. RESEARCH DESIGN AND METHODS: Patients were identified through the French sarcoma diagnostic laboratory at Institut Curie through samples analyzed by RT-qPCR or whole-transcriptome sequencing. RESULTS: From 2001 to 2019, 65 NTRK fusion tumors were identified within 2120 analyses (3.1%): 58 by RNA sequencing (including 20 after RT-qPCR analysis) and 7 exclusively by RT-qPCR. Of the 61 patients identified, 37 patients had infantile soft tissue or kidney fibrosarcomas (IFS), 15 other mesenchymal (Other-MT) and nine central nervous system (CNS) tumors. They encompassed 14 different tumor types with variable behaviors. Overall, 53 patients had surgery (3 mutilating), 38 chemotherapy (20 alkylating agents/anthracycline), 11 radiotherapy, two 'observation strategy' and 13 received TRKi. After a median follow-up of 61.0 months [range, 2.5-226.0], 10 patients died. Five-year overall survival is, respectively, 91.9% [95%CI, 83.5-100.0], 61.1% [95%CI, 34.2-100.0] and 64.8% [95%CI, 39.3-100.0] for IFS, Other-MT, and CNS groups. CONCLUSIONS: NTRK-fusion positive tumors are rare but detection is improved through RNA sequencing. TRKi could be considered at diagnosis for CNS NTRK-fusion positive tumors, some IFS, and Other-MT. TRIAL REGISTRATION: Not adapted.

Deep learning predicts patients outcome and mutations from digitized histology slides in gastrointestinal stromal tumor.

Risk assessment of gastrointestinal stromal tumor (GIST) according to the AFIP/Miettinen classification and mutational profiling are major tools for patient management. However, the AFIP/Miettinen classification depends heavily on mitotic counts, which is laborious and sometimes inconsistent between pathologists. It has also been shown to be imperfect in stratifying patients. Molecular testing is costly and time-consuming, therefore, not systematically performed in all countries. New methods to improve risk and molecular predictions are hence crucial to improve the tailoring of adjuvant therapy. We have built deep learning (DL) models on digitized HES-stained whole slide images (WSI) to predict patients' outcome and mutations. Models were trained with a cohort of 1233 GIST and validated on an independent cohort of 286 GIST. DL models yielded comparable results to the Miettinen classification for relapse-free-survival prediction in localized GIST without adjuvant Imatinib (C-index=0.83 in cross-validation and 0.72 for independent testing). DL splitted Miettinen intermediate risk GIST into high/low-risk groups (p value = 0.002 in the training set and p value = 0.29 in the testing set). DL models achieved an area under the receiver operating characteristic curve (AUC) of 0.81, 0.91, and 0.71 for predicting mutations in KIT, PDGFRA and wild type, respectively, in cross-validation and 0.76, 0.90, and 0.55 in independent testing. Notably, PDGFRA exon18 D842V mutation, which is resistant to Imatinib, was predicted with an AUC of 0.87 and 0.90 in cross-validation and independent testing, respectively. Additionally, novel histological criteria predictive of patients' outcome and mutations were identified by reviewing the tiles selected by the models. As a proof of concept, our study showed the possibility of implementing DL with digitized WSI and may represent a reproducible way to improve tailoring therapy and precision medicine for patients with GIST.

Impact of age on survival according to molecular tumor findings in children and adolescents with soft-tissue and bone sarcoma: The BIOSCA project.

BACKGROUND: Adolescents (15-19 years) with sarcoma are known to have significantly worse survival than children (0-14 years). One possible reason may be that the adolescent sarcomas exhibit specific biological characteristics resulting in differences in clinical presentation and treatment resistance behaviors. The BIOSCA project aims to further explore these age-related differences in survival accounting for molecular tumor characteristic in children and adolescents with sarcoma. METHODS: A retrospective national population-based observational study with documented somatic genetic analyses was conducted between 2011 and 2016 of all patients aged from 0 to 17 years with a diagnosis of sarcoma using the National Registry of Childhood Cancers Database. RESULTS: A total of 1637 children (0-9years: 40%), preadolescents (10-14years: 35%) and adolescents (15-17 years: 25%) with a diagnosis of bone (N = 845) or soft-tissue (N = 792) sarcoma were included. Adolescents had significantly worse outcome for undifferentiated small round cell sarcoma (USRCS), alveolar rhabdomyosarcoma (ARMS), and epithelioid sarcoma. Five-year overall survivals were worse among CIC-rearranged USRCS cases (47% [95%CI:21-69]) as compared to other USRCS, and PAX3::FOXO1 ARMS patients (44% [95%CI:32-55]) as compared to other ARMS. Adjusting for stage and genomic-profiling status, adolescents with USRCS were 1.6-fold more likely to die than children (P = 0.05), while the difference in survival between age of ARMS patients was weaken. Indeed, the prevalence of PAX3::FOXO1 increased significantly with age. CONCLUSION: Age was an independent prognostic factor of outcome only in patients with USRCS, while the association between age and survival of patients with ARMS could be partly explained by differences in prevalence of PAX3::FOXO1.

Oral vinorelbine in young patients with desmoid-type fibromatosis.

BACKGROUND: Desmoid-type fibromatosis are rare intermediate tumors in children and adolescents. Owing to local aggressiveness and relapse, systemic treatment for symptomatic advanced or progressive forms is recommended. Following promising results in adult patients, oral vinorelbine is investigated in young patients. METHODS: A retrospective review of young patients (<25 years old) with advanced or progressive desmoid type fibromatosis treated with oral vinorelbine in eight large centers of the Société Française des Cancers de l'Enfant was performed. In addition to tumor assessment according to RECIST 1.1, pre-treatment and during-treatment imagery were reviewed centrally to assess tumor volume and estimate fibrosis score through the change in percentage in hypoT2 signal intensity. RESULTS: From 2005 to 2020, 24 patients (median age 13.9 years [range, 1.0-23.0]) received oral vinorelbine. Median number of prior systemic lines of treatment was 1 (range, 0-2), mainly based on intravenous low dose methotrexate and vinblastine. Before vinorelbine initiation, all patients had a progressive disease: radiological for 19, radiological and clinical (pain) for three and only clinical for two. Oral vinorelbine was delivered for a median duration of 12 months (range, 1-42). The toxicity profile was favorable, with no grade 3-4 event. Overall response estimated on 23 evaluable patients according to RECIST 1.1 criteria was three partial responses (13%), 18 stabilization (78%) and two progressive disease (9%). Overall progression-free survival was 89.3% (95% confidential intervals 75.2-100) at 24 months. Four stable tumors according to standard RECIST criteria displayed a partial response with > 65% tumor volume reduction. Among 21 informative patients, the estimated fibrosis score decreased for 15 patients, was stable for four patients and increased for two patients. CONCLUSION: Oral vinorelbine seems to be effective to control advanced or progressive desmoid type fibromatosis in young patients, with a well-tolerated profile. These results support testing this drug as first-line alone or in combination to improve response rate while preserving quality of life.

Outcome of patients with undifferentiated embryonal sarcoma of the liver treated according to European soft tissue sarcoma protocols.

BACKGROUND: To assess the outcomes of pediatric patients with undifferentiated embryonal sarcoma of the liver (UESL) and treatment including at least surgery and systemic chemotherapy. METHODS: This study included patients aged up to 21 years with a pathological diagnosis of UESL prospectively enrolled from 1995 to 2016 in three European trials focusing on the effects of surgical margins, preoperative chemotherapy, use of radiotherapy (RT), and chemotherapy. RESULTS: Out of 65 patients with a median age at diagnosis of 8.7 years (0.6-20.8), 15 had T2 tumors, and one had lymph node spread, 14 were Intergroup Rhabdomyosarcoma Study (IRS) I, nine IRS II, 38 IRS III, and four IRS IV. Twenty-eight upfront surgeries resulted in five operative spillages and 11 infiltrated surgical margins, whereas 37 delayed surgeries resulted in no spillages (p = .0119) and three infiltrated margins (p = .0238). All patients received chemotherapy, including anthracyclines in 47. RT was administered in 15 patients. With a median follow-up of 78.6 months, 5-year overall and event-free survivals (EFS) were 90.1% (95% confidence interval [CI]: 79.2-95.5) and 89.1% (95% CI: 78.4-94.6), respectively. Two out four local relapses had previous infiltrated margins and two out of three patients with metastatic relapses received reduced doses of alkylating agents. Infiltrated margins (p = .1607), T2 stage (p = .3870), use of RT (p = .8731), and anthracycline-based chemotherapy (p = .1181) were not correlated with EFS. CONCLUSIONS: Multimodal therapy improved the outcome of UESL. Neoadjuvant chemotherapy for pediatric patients increases the probability of complete surgical resection. The role of anthracyclines and RT for localized disease remains unclear.

Efficacy and Safety of Adjuvant Radiotherapy in Re-excised Soft-tissue Sarcoma After Unplanned Resection.

INTRODUCTION: The objective of this study was to evaluate the efficacy and safety of adjuvant radiotherapy (aRT) in patients with soft-tissue sarcoma (STS) re-excised after unplanned tumor resection (UPR). MATERIALS AND METHODS: From 2000 to 2015, we retrospectively evaluated patients with STS of limb or trunk who underwent post-UPR re-excision in our expert center and received or not aRT. RESULTS: Median follow-up was 121 months (IQR 94-165). Among the 145 patients, 37 were not treated with aRT (no-RT) and 108 received aRT with a median radiation dose of 50 Gy (IQR 50-60). At 10 years, patients in the aRT and no-RT groups showed a cumulative incidence of local failure (10y-LF) of 14.7% and 37.7%, and a local recurrence-free survival (10y-LRFS) of 61.3% and 45.8%, respectively. Multivariate analysis identified aRT and age ≥70 years as independent predictors of both LF and LRFS, while grade 3 and deep-seated tumor were independent predictors of LRFS. In overall population, 10-year distant metastasis-free survival (10y-DMFS) and overall survival (10y-OS) were 63.7% and 69.4%. In multivariate analyses, age ≥70 years, grade 3, and deep-seated lesion were associated with shorter DMFS and OS. Acute severe adverse events were not significantly increased in aRT group (14.8% vs. 18.1%, P = .85) but dramatically increased if radiation dose exceeded 50 Gy (risk ratio 2.96 compared to ≤50 Gy, P = .04). CONCLUSION: In STS patients re-excised after UPR, 50 Gy aRT was safe and associated with reduced LF and longer LRFS. It seems to be beneficial even in absence of residual disease or in absence of initial adverse prognostic factors.

A Combination of MTAP and p16 Immunohistochemistry Can Substitute for CDKN2A Fluorescence In Situ Hybridization in Diagnosis and Prognosis of Pleural Mesotheliomas.

CONTEXT.­: Homozygous deletion (HD) of CDKN2A is one of the most frequent genetic abnormalities in pleural mesotheliomas. HD of CDKN2A by fluorescence in situ hybridization (FISH) is a reliable marker of malignancy in mesothelial proliferations; however, evaluation of CDKN2A deletion requires FISH. The 9p21 locus includes both CDKN2A and MTAP (methylthioadenosine phosphorylase); the latter is frequently codeleted with CDKN2A. OBJECTIVE.­: To examine the question of whether immunohistochemistry for MTAP and p16, the protein product of CDKN2A, can serve as a surrogate for CDKN2A HD by FISH. DESIGN.­: A random selection of 125 pleural mesothelioma cases was divided into 3 groups for evaluation of p16 and MTAP expression compared with FISH for CDKN2A deletion: 53 with HD, 39 with heterozygous deletion, and 33 without deletion. RESULTS.­: By itself, loss of p16 nuclear expression (<1% staining) showed a high sensitivity (96%) but low specificity (43%) for CDKN2A HD by FISH. MTAP cytoplasmic expression loss (≤30% staining) showed a 97% specificity and 69% sensitivity. The combination of p16 nuclear (<1% staining) and MTAP cytoplasmic (≤30% staining) loss demonstrated both high specificity (96%) and high sensitivity (86%). Patients with retained p16 expression (≥1%) had the best prognosis, whereas a p16 (<1%)/MTAP loss combination was associated with a dismal prognosis. CONCLUSIONS.­: MTAP immunohistochemical staining is a valid surrogate marker for CDKN2A HD by FISH; however, to obtain the same accuracy as the FISH assay, a combination of nuclear p16 and cytoplasmic MTAP staining is recommended. These findings correlate with prognosis.

Prognostic factors of the synovial sarcoma of the extremities: imaging does matter.

OBJECTIVES: Synovial sarcomas (SS) of the extremities are rare soft tissue sarcomas that are more common in young adults. We deciphered the imaging phenotype of SS with the aim to determine if imaging could provide an incremental value to currently known prognostic factors (PF)-age and histological grade-to predict long-term overall survival (OS). METHODS: This retrospective multicenter study included consecutive pediatric and adult patients with synovial sarcomas of the extremities from December 2002 to August 2020. Inclusion criteria were (i) a follow-up greater than 5 years and (ii) available pre-therapeutic MRI. A subset analysis included MRI and CT-scan. Clinical, pathological, and imaging variables were collected in all patients. The primary endpoint was to evaluate the association of these variables with OS using univariate and multivariate Cox regressions. RESULTS: Out of 428 patients screened for eligibility, 98 patients (mean age: 37.1 ± 15.2 years) were included (MRI: n = 98/98, CT scan: n = 34/98; 35%). The median OS was 75.25 months (IQR = 55.50-109.12) and thirty-six patients (n = 36/98;37%) died during follow-up. The recurrence rate was 12.2% (n =12/98). SS lesions were mostly grade 2 (57/98; 58%). On MRI, SS had a mean long-axis diameter of 67.5 ± 38.3 mm. On CT scan, 44% (15/34) were calcified. Grade (hazard ratio [HR] = 2.71; 95%CI = 1.30-5.66; p = 0.008), size of the lesions evaluated on MRI (HR = 1.02; 95% CI = 1.01-1.03; p < 0.001), and calcifications on CT scan (HR = 0.10; 95% CI = 0.02-0.50; p = 0.005) were independent PF of OS. CONCLUSIONS: This study demonstrated that imaging biomarkers can be used to predict long-term outcome in patients with SS. Strikingly, the presence of calcifications on CT scan is associated with favorable outcome and provides an incremental value over existing PF such as age, grade, and size. KEY POINTS: • Beyond its diagnostic value, MRI is a pre-operative prognostic tool in synovial sarcomas of the extremities since the size of the lesion is an important prognostic factor. • Calcifications on CT scans are independently and significantly associated with prolonged overall survival.

Expanding the molecular spectrum of tenosynovial giant cell tumors.

Background: While great advances in clinical and pathological description of tenosynovial giant cell tumors (TGCT) have been made, TGCT molecular heterogeneity represents an ongoing challenge. The canonical oncogenic fusion CSF1::COL6A3 is not systematically observed, suggesting that other oncogenic mechanisms are involved in tumorigenesis. This study aims to explore by RNA sequencing a retrospective series of tumors diagnosed as TGCT, in order to provide a better description of their molecular landscape and to correlate molecular features with clinical data. Methods: We analyzed clinicopathological data and performed whole-exome RNA sequencing on 41 TGCT samples. Results: RNAseq analysis showed significant higher CSF1 and CSF1-R expression than a control panel of 2642 solid tumors. RNA sequencing revealed fusion transcripts in 14 patients including 6 not involving CSF1 and some previously unreported fusions. Unsupervised clustering on the expression profiles issued from this series suggested two distinct subgroups: one composed of various molecular subtypes including CSF1 and FN1 rearranged samples and one composed of four tumors harboring an HMGA2::NCOR2 fusion, suggesting distinct tumor entities. Overall, 15 patients received at least one systemic anti-CSF1R treatment and clinical improvement was observed in 11 patients, including patients from both clusters. Discussion: This study reported molecular heterogeneity in TGCT, contrasting with the clinical and pathological homogeneity and the ubiquitous high CSF1 and CSF1R expression levels. Whether molecular diversity may impact the efficacy of systemic treatments needs to be further investigated.

Overall survival in patients with re-excision of positive microscopic margins of limb and trunk wall soft tissue sarcoma operated outside of a reference center: a nationwide cohort analysis.

BACKGROUND: This French nationwide NETSARC exhaustive prospective cohort aims to explore the impact of systematic re-excision (RE) as adjuvant care on overall survival (OS), local recurrence free survival (LRFS), and local and distant control (RFS) in patients with soft tissue sarcoma (STS) with positive microscopic margins (R1) after initial resection performed outside of a reference center. METHODS: Eligible patients had experienced STS surgery outside a reference center from 2010 to 2017, and had R1 margins after initial surgery. Characteristics and treatment comparisons used chi-square for categorical variables and Kruskall-Wallis test for continuous data. Survival distributions were compared in patients reexcised (RE) or not (No-RE) using a log-rank test. A Cox proportional hazard model was used for subgroup analysis. RESULTS: A total of 1,284 patients had experienced initial STS surgery outside NETSARC with R1 margins, including 1,029 patients with second operation documented. Among the latter, 698 patients experienced re-excision, and 331 were not re-excised. Characteristics were significantly different regarding patient age, tumor site, tumor size, tumor depth, and histotype in the population of patients re-excised (RE) or not (No-RE). The study identified RE as an independent favorable factor for OS (HR 0.36, 95%CI 0.23-0.56, p<0.0001), for LRFS (HR 0.45, 95%CI 0.36-0.56, p<0.0001), and for RFS (HR 0.35, 95%CI 0.26-0.46, p<0.0001). CONCLUSION: This large nationwide series shows that RE improved overall survival in patients with STS of extremities and trunk wall, with prior R1 resection performed outside of a reference center. RE as part of adjuvant care should be systematically considered.

No Geographical Inequalities in Survival for Sarcoma Patients in France: A Reference Networks' Outcome?

The national reference network NETSARC+ provides remote access to specialized diagnosis and the Multidisciplinary Tumour Board (MTB) to improve the management and survival of sarcoma patients in France. The IGéAS research program aims to assess the potential of this innovative organization to address geographical inequalities in cancer management. Using the IGéAS cohort built from the nationwide NETSARC+ database, the individual, clinical, and geographical determinants of the 3-year overall survival of sarcoma patients in France were analyzed. The survival analysis was focused on patients diagnosed in 2013 (n = 2281) to ensure sufficient hindsight to collect patient follow-up. Our study included patients with bone (16.8%), soft-tissue (69%), and visceral (14.2%) sarcomas, with a median age of 61.8 years. The overall survival was not associated with geographical variables after adjustment for individual and clinical factors. The lower survival in precarious population districts [HR 1.23, 95% CI 1.02 to 1.48] in comparison to wealthy metropolitan areas (HR = 1) found in univariable analysis was due to the worst clinical presentation at diagnosis of patients. The place of residence had no impact on sarcoma patients' survival, in the context of the national organization driven by the reference network. Following previous findings, this suggests the ability of this organization to go through geographical barriers usually impeding the optimal management of cancer patients.

Identification of a novel translocation producing an in-frame fusion of TAF15 and ETV4 in a case of extraosseous Ewing sarcoma revealed in the prenatal period.

Ewing sarcoma (ES) is a highly malignant round cell sarcoma, characterized by gene fusion involving FET (FUS, EWSR1, TAF15) and ETS family genes, respectively. The involvement of the EWSR1 gene has been reported in approximately 90% of cases of ES, with the EWSR1::FLI1 fusion being the most frequent. We report the case of a newborn with a localized soft tissue paravertebral neoplasm diagnosed prenatally. Histopathology and immunophenotype were consistent with a CD99 + , NKX2.2 + undifferentiated round cell sarcoma (URSC); whole-exome RNA-sequencing demonstrated an undescribed in-frame TAF15::ETV4 fusion transcript, while consensus clustering analysis showed high transcriptomic proximity to the ES group. Given clinical context, high tumor chemosensitivity to ES conventional drugs, morphological characteristics, nature of the fusion partners involved, and high transcriptomic proximity to bona fide ESs, this case may represent a new genetic variant of ES.