Clinico-demographic characteristics and outcomes of radiation-induced sarcomas (RIS): a CanSaRCC study

Background

Radiation-induced sarcomas (RIS) tend to have aggressive behaviour and because of their rarity, the most appropriate management for these malignancies is uncertain.

Objectives

Using the Canadian Sarcoma Research and Clinical Collaboration (CanSaRCC) database, a national sarcoma registry, we aimed to investigate prognostic factors and outcomes for RIS.

Design

Retrospective study of RIS patients treated from 1996 to 2021 at three Canadian centres.

Methods

RIS was defined as a sarcoma arising in a previously irradiated field following a 3+ year latency period, whose histology was distinct from the initially irradiated tumour. Clinicopathologic and treatment-related information was extracted from the CanSaRCC database. Overall survival (OS) was defined as the time from RIS diagnosis to death from any cause. Response rate (RR) to neoadjuvant chemotherapy (NACT) was based on physician assessment. Time-to-event analyses were estimated using the Kaplan-Meier method, with Cox regression for multivariate analysis. We considered a two-tailed p-value of <0.05 as statistically significant.

Results

One hundred seven tumours met the criteria for RIS and were divided into three subgroups: breast angiosarcoma (BAS, n = 54), osteosarcoma (OST, n = 16), and other soft-tissue sarcomas (STS, n = 37). Patients were mostly female (n = 85, 79%), treated initially for breast carcinomas (n = 54, 50.5%), and diagnosed with high-grade tumours (n = 61/71, 86%). None had evidence of synchronous metastasis. Patients with OST were younger (median age: 48 years, p < 0.001), and BAS had the shortest latency interval (8 versus 18 years for OST/STS, p < 0.001). Most patients underwent surgery, 76% (n = 76/100) R0; 24% (n = 26) received radiation therapy, mostly (n = 15, 57.7%) neoadjuvant. Among those receiving chemotherapy, 30 (75%) underwent NACT; among patients with documented response assessment, the RR was 68% (n = 17/25), being even higher in the BAS population (89.5%, n = 13/17). Median OS was 53 months (95% CI 34-101), with a 5-year OS of 47.6%; larger tumour size, high histologic grade and older age were independent prognostic factors for worse OS.

Conclusion

Surgery is standard, and NACT might be useful to downsize large lesions, especially in BAS patients. Raising RIS awareness is fundamental to promoting appropriate management and fostering research through multi-institutional collaborations.

Mutations involving TGFB and MAPK may be associated with malignancy in granular cell tumors

Granular cell tumors (GrCTs) are mesenchymal neoplasms of presumed schwannian differentiation that may present as solitary or multifocal lesions with excision usually being curative. A minority of cases, however, show histological features associated with an increased risk for metastasis and are highly aggressive leading to death in about a third of cases. While benign and malignant cases have been shown to harbor mutations in the H + ATPase genes, there is only limited data examining molecular aberrations associated with malignancy. The departmental archives were searched for cases of atypical/malignant GrCTs. Clinical and histopathological features were noted. Whole-exome sequencing was performed. Three cases of malignant GrCTs and one case of atypical GrCTs were included. All three malignant tumors metastasized to distant sites with a median disease-free survival of 16 months and an overall follow-up time of 35 months. Whole-exome sequencing showed mutations involving TGFβ and MAPK pathways in all four tumors. Although the cohort size is small, our preliminary findings suggest that mutations involving the TGFβ and MAPK pathways may be associated with tumor progression or malignant transformation in GrCT pathogenesis.

Functional genomics of human clear cell sarcoma: genomic, transcriptomic and chemical biology landscape for clear cell sarcoma

BACKGROUND

Systemic therapy for metastatic clear cell sarcoma (CCS) bearing EWSR1-CREB1/ATF1 fusions remains an unmet clinical need in children, adolescents, and young adults.

METHODS

To identify key signaling pathway vulnerabilities in CCS, a multi-pronged approach was taken: (i) genomic and transcriptomic landscape analysis, (ii) integrated chemical biology interrogations, (iii) development of CREB1/ATF1 inhibitors, and (iv) antibody-drug conjugate testing (ADC). The first approach encompassed DNA exome and RNA deep sequencing of the largest human CCS cohort yet reported consisting of 47 patient tumor samples and 8 cell lines.

RESULTS

Sequencing revealed recurrent mutations in cell cycle checkpoint, DNA double-strand break repair or DNA mismatch repair genes, with a correspondingly low to intermediate tumor mutational burden. DNA multi-copy gains with corresponding high RNA expression were observed in CCS tumor subsets. CCS cell lines responded to the HER3 ADC patritumab deruxtecan in a dose-dependent manner in vitro, with impaired long term cell viability.

CONCLUSION

These studies of the genomic, transcriptomic and chemical biology landscape represent a resource 'atlas' for the field of CCS investigation and drug development. CHK inhibitors are identified as having potential relevance, CREB1 inhibitors non-dependence of CCS on CREB1 activity was established, and the potential utility of HER3 ADC being used in CCS is found.

Mid and long-term overall survival after carcinologic resections of thyroid cancer bone metastases

Background

Bone metastases in thyroid cancer impair the patient's quality of life and prognosis. Interestingly, wide margins resection as the surgical treatment of bone metastases might improve the overall survival (OS). Nonetheless, data are lacking regarding the potential benefits of this strategy.

Methods

In order to assess the OS of patients with thyroid cancer after a bone metastases carcinologic resection, a retrospective multicentric study was performed, evaluating the 1, 5, 10 and 15 years-OS along with the potential prognosis associated factors.

Results

40 patients have been included in this multicentric study, with a mean follow-up after surgery of 46.6 ± 58 months. We observed 25 (62.5%) unimestastatic patients and 15 multimetastatic patients (37.5%). The median overall survival after resection was 48 ± 57.3 months. OS at 1, 5, 10, and 15 years was respectively 76.2%, 63.6%, 63.6%, and 31.8%. Survival for patients with a single bone metastasis at 15 year was 82.3%, compared with 0.0% (Log Rank, p = 0.022) for multi-metastatic bone patients.

Conclusions

This study advocates for an increased long term 10-year OS in patients with thyroid cancer, after resection of a single bone metastasis, suggesting the benefits of this strategy in this population.

Circulating tumor DNA (ctDNA) detection of molecular residual disease (MRD) as a potential biomarker in localized soft tissue sarcoma (STS)

11547

Background: Surgery and (neo)adjuvant radiotherapy are the mainstay curative treatments for localized STS. Despite treatment, approximately 50% of STS patients (pts) experience metastatic relapse and routine use of adjuvant systemic therapy (AST) remains controversial. The presence of ctDNA following curative treatment of STS is a potential biomarker for MRD and may identify patients who benefit from AST. Given the genomic heterogeneity of STS, a histology-agnostic approach to ctDNA detection in this population is desirable. Methods: Pts with localized, high risk (size ≥ 5cm, grade ≥ 2) disease were enrolled prior to (neo) adjuvant radiotherapy and surgery. Blood for ctDNA was collected at diagnosis; post-radiotherapy, post-surgery and every 3 months for up to 2 years. Whole exome sequencing (WES) of archival tumor- and matched buffy coat-DNA were carried out to identify somatic variants. Personalized and tumor-informed, multiplex PCR next generation sequencing-based ctDNA assay (Signatera™ assay) was performed on plasma obtained at the serial timepoints. A sample level positive call required ≥ 2 variants above a confidence calling threshold. Absolute ctDNA levels were expressed as mean tumor molecules per milliliter (MTM/ml) of plasma, based on variant allele frequencies and quantity of cell free DNA. Standard radiologic surveillance (every 3 months) was performed following surgery. The primary endpoint was a ctDNA detection rate of 70% at diagnosis. Secondary endpoints included MRD detection and correlation of ctDNA levels with disease relapse. Results: Seventy-six plasma samples from 10 pts [8 males and 2 females; median age 64 years (range 46–84)] were obtained prospectively. STS subtypes were undifferentiated pleomorphic sarcoma (n = 4), myxofibrosarcoma (n = 2), dedifferentiated liposarcoma (n = 2), myxoid liposarcoma (n = 1), and pleomorphic liposarcoma (n = 1). All tumors successfully underwent WES with adequate data quality for Signatera™ assay design. The personalized ctDNA assay was performed on a median of 7 plasma samples per patient (range: 5 – 10). ctDNA was detected in 7 pts (70%) at diagnosis, with median ctDNA level of 1.6 MTM/ml (range: 0.2 – 137.8), achieving the study primary endpoint. Immediate post-surgery samples were negative in all pts. However, ctDNA was detected in 2 out of 2 pts who developed metastatic disease during follow-up. Conclusions: Personalized tumor-informed ctDNA assays in localized high-risk STS at diagnosis are feasible. In this series, all patients had undetectable levels of ctDNA post-surgery and patients who experienced disease relapse demonstrated a detectable rise in ctDNA levels. Further interrogation of this approach for detection of post-treatment MRD as a possible biomarker of benefit from AST is ongoing.

Management of giant cell tumors of the distal radius: a systematic review and meta-analysis

PURPOSE

The treatment of giant cell tumors (GCT) of the distal radius remains challenging, with no consensus on the optimal surgical management. Surgical management remains the mainstay of treatment with options including intralesional curettage and en-bloc resection with reconstruction. The objective of this systematic review and meta-analysis was to evaluate and compare the outcomes of these two procedures.

METHODS

Using OVID-Medline and Embase databases, a systematic literature search was performed. Comparative studies, assessing intralesional curettage and en-bloc resection in patients with GCTs of the distal radius, were included. Data regarding rates of local recurrence, metastasis, overall complications, and functional outcomes, were collected and analyzed. The ROBINS-I tool was utilized for risk of bias appraisal within each study outcome.

RESULTS

Thirteen studies (n = 373 patients) reporting on 191 intralesional curettage procedures and 182 en-bloc resections were included in the analysis. The average age of participants was 31.9 (SD ± 2.4) years and average follow-up was 7.1 (SD ± 3.6) years. Patients that underwent intralesional curettage were more likely to develop local recurrence (Risk Ratio (RR) 3.3, 95% CI, [2.1, 5.4], p < 0.00001) when compared to patients that underwent en-bloc resection. In Campanacci grade 3 lesions, the risk for local recurrence was 5.9 (95% CI, [2.2, 16.3], p = 0.0006) times higher in patients that received intralesional curettage. Patients that underwent intralesional curettage showed an 84% reduction in the relative risk of developing overall complications compared to en-bloc resection (95% CI, [0.1, 0.4], p < 0.00001), and a larger decrease in Visual Analog Scale and lower Disabilities of the Arm, Shoulder, and Hand (DASH) scores (p < 0.00001). Risk ratio for developing a local recurrence, with PMMA versus bone graft following an intralesional procedure was not significant (RR 1.2, 95% CI, [0.6, 2.6], p = 0.62).

CONCLUSIONS

In the surgical management of GCT of the distal radius, intralesional curettage increased local recurrence compared to en-bloc resection with reconstruction, particularly in grade 3 tumors. However, it led to significantly fewer operative complications, lower pain scores, and improved functional outcomes compared to en-bloc resection. Both treatment options remain relevant in the contemporary management of GCTs of the distal radius. Surgical decision making should include both patient and tumor factors when determining the optimal treatment strategy for these patients. LEVEL 3 EVIDENCE: Meta-analysis of Level 3 studies.

168 Expanding and characterizing tumor infiltrating lymphocytes from myxofibrosarcoma and undifferentiated pleomorphic sarcoma

Background

Sarcoma is a group of rare bone and soft tissue tumors with over 50 distinct subtypes. Survival rate ranges widely due to the lack of efficacious treatments. Immunotherapy, such as adoptive cell therapy (ACT), has drawn significant interest due to its minimal toxicity. In ACT, tumor infiltrating lymphocytes (TILs) are isolated from patients, expanded, and autologously infused back. We recently observed TILs’ presence in Undifferentiated Pleomorphic Sarcoma (UPS) and Myxofibrosarcoma (MFS) tumors and found that tumor’s PD-L1 overexpression is correlated with better clinical outcome in UPS but not MFS.1 The Th1 anti-tumoral inflammatory pathway was highly activated in the former cohort, which may explain the favorable outcome. We hypothesize that there are phenotypic and functional differences between TILs of UPS with differential PD-L1 expression, which may be related to clinical outcomes. However, sarcoma TILs are rare and challenging to culture, which significantly impedes their studies. We first aim to robustly expand sarcoma TILs to sufficient numbers.

Methods

Tumors’ PD-L1 expression was determined by RT-qPCR (table 1). To initiate the tumor-fragment (TF) method of TIL culturing, primary tumors were fragmented and cultured in IMDM, IL-2, and 10% HSA. We further optimized the TF protocol to expand rare sarcoma TILs. Rapid expansion protocol (REP) with anti-CD3/anti-CD28 co-stimulating beads was employed for additional expansion. During REP, TILs were co-treated with gamma-chain cytokines (IL-2, 7, 15, 21).

Results

Of the 15 MFS TIL populations expanded, only 40% achieved sufficient growth (1x106) for analysis (figure 1A). Our optimized TF protocol expanded TILs from 8 UPS cases with a 62.5% success rate (figure 1B). UPS TILs were further stimulated with REP and various gamma-chain cytokine treatments. In ACT, prolonged culturing with IL-2 is known to cause activation-induced cell death, problematic in clinical treatments. We demonstrated that treatments with a Trio-cocktail (IL-7, 15, and 21) or IL-15 alone can achieve TIL proliferation comparable to that of IL-2 (figure 2).

Abstract 168 Figure 1

Initial TIL Culturing with Tumor Fragment Method. Figure A.. The traditional tumor fragment protocol was used to expand TILs of four MFS cases. TILs were cultured and expanded from primary tumor fragments in IL-2 (6000IU/mL) supplemented complete media (CM) over four weeks in duration. Fifteen TIL populations were derived from the four MFS cases. Populations were categorized based on their growth rates and labeled as ‘1’ or ‘2’ representing ‘fast’ or ‘slow’ growing TILs, respectively. Additional populations ‘A’ and ‘B’ represent biological replicates. Population TIL164 ‘2’ had no replicates. At Week 4, populations’ cell counts were determined via hemocytometer. As shown, only 6 out of 15 populations achieved > 1x10^6 cells (40% success rate). Figure B. An optimized tumor fragment protocol was used to expand TILs of eight UPS cases. Optimization includes shortening the culturing duration from four weeks to two weeks, reducing frequency of cell culture disruption, and adjusting cell culture environments. TILs were expanded from primary tumor fragments in CM over two weeks in duration. At Week 2, populations’ cell counts were determined via hemocytometer. As shown, 5 out of 8 cases achieved >1x10^6 cells (62.5% success rate).

Abstract 168 Figure 2

Gamma-chain cytokine treatments of UPS TILs. Gamma-chain cytokine treatments of UPS TILs with CD3/CD28 stimulation. Magnetic Dynabeads coated with CD3 and CD28 monoclonal antibodies were used to stimulate cells at a bead to cell ratio of 1:3. In ACT, IL-2 is a gold-standard cytokine that facilitates potent T-cell growth. However, it is known to cause activation-induced cell death. Resulting TIL population also possesses an exhausted-effector phenotype with low durability. UPS TIL Case 52 and Case 166 were treated with various interleukins during two weeks of REP, including gamma-chain IL-7, 15, 21 and inflammatory IL-12. IL-7, IL-12, and IL-21 individually did not elicit significant T-cell growth. IL-15 alone and in combination with IL-7 and IL-21 yield growth comparable to IL-2. IL-2 was obtained from Novartis (50ng/mL). All other cytokines were obtained from PeproTech (25ng/mL).

Abstract 168 Table 1

Tumor PD-L1 RNA Expression. Four MFS and eight UPS cases were processed. Tumors’ PD-L1 RNA expression was determined via RT-qPCR and evaluated as a ratio with the housekeeping gene STAM2. TIL359’s PD-L1 status has yet to be evaluated.

Conclusions

Sarcoma infiltrates are difficult to culture, and their roles remain largely unstudied. By optimizing the TF protocol in conjunction with anti-CD3/CD28 treatments, we developed a robust in vitro pipeline to expand rare sarcoma TILs, enabling downstream characterization. We also demonstrated the potential for alternate gamma-chain cytokines to favorably replace IL-2 during TIL expansion. Future phenotypic and functional evaluation of UPS TILs would elucidate the impact of tumors’ differential PD-L1 expression on UPS patients‘ prognoses. These findings would inform the implementation of ACT in sarcoma treatments.

References

Wunder J, Lee M, Nam J, Lau B, Dickson B, Pinnaduwage D, Bull S, Ferguson P, Seto A, Gokgoz N, Andrulis I. Osteosarcoma and soft-tissue sarcomas with an immune infiltrate express PD-L1: relation to clinical outcome and Th1 pathway activation. Onco Immunology 2020;9: e1737385-1- e1737385-13.

Ethics Approval

Patients provided signed consent before study entry, as approved by Mount Sinai Hospital’s Ethics Board (REB#01-0138-U).

The impact of multimodality therapies in marginally inoperable soft tissue sarcomas (STS): The Toronto Sarcoma Program (TSP) experience

11548

Background: The mainstay therapy of operable STS remains surgery, which may include (neo)adjuvant therapies. Within the TSP, marginally inoperable STS are often treated with sequential chemo (CTX) and radiation (RT) therapy, followed by surgery (SX). Herein we present our experience of multi-modality therapies for marginally inoperable STS patients (pts). Methods: This was a dual-center, single program, retrospective review. Pts were included if deemed to have marginally inoperable primary or recurrent STS, as determined at the TSP tumor board. Pts included must have had CTX with the intent of having RT and SX after. Pts demographics, treatment details and clinical outcomes data were collected. Relapse free survival (RFS) and overall survival (OS) were estimated using the Kaplan-Meier method. Multivariate analysis of the influence of disease characteristics and treatment on outcomes was assessed using Cox regression. Results: From June 2005 to May 2019, 75 pts were identified. Median age was 52 years (range 16-72). Pts were predominantly male (55%). Histological subtypes included dedifferentiated liposarcoma (29%), leiomyosarcoma (27%), synovial sarcoma (19%) and others (25%). Primary tumor was located in the retroperitoneum (48%), extremity (23%), pelvis (12%), thorax (9%), and other sites (8%). All pts had doxorubicin and ifosfamide CTX (median 4 cycles; range 1-6), while RT dose delivered was 50.4Gy/28 fractions in 58 (77%) of cases. Twenty three pts (31%) achieved partial response, 40 pts (53%) had stable disease and 12 pts (16%) had progression of disease (PD) on CTX, of which half (8%) did not undergo further treatment. Nine pts (12%) underwent CTX followed by SX due to significant response, 9 pts (12%) underwent CTX and RT without SX due to persistent tumor unresectability or PD. The final 50 pts (67%) completed multi-modality treatment (CTX, RT & SX). Overall, 59 pts (79%) had SX; negative margins were achieved in 53 (71%). 19 pts (25%) had postoperative complications, causing death in 2 pts (2.7%). With a median follow-up of 72 months, median RFS and OS were 26.9 months (95% CI: 0-86.0), and 65 months (95% CI: 13.5-116.4). Extremity location was associated with superior RFS (median not reached [NR], HR 0.28 95% CI 0.09-0.83, p = 0.022), and OS (median NR, HR 0.29 95% CI 0.09-0.90, p = 0.032). Receipt of RT was associated with superior RFS (median NR, HR 0.23 95% CI 0.10-0.52, p < 0.001); and OS (median NR, HR 0.21 95% CI 0.09-0.50, p < 0.001). Pts who had PD after CTX were associated with poor outcomes - RFS (median 4.7 months, HR 2.03 95% CI 0.61-6.76, p = 0.24); and OS (median 21.9 months, HR 2.48 95% CI 0.73-8.47, P = 0.144). Conclusions: Multi-modality approach resulted in successful resection for most pts with marginally inoperable STS. Extremity location and RT administration were associated with better RFS and OS, while progression on CTX confers worse survival outcomes.

Complete pathological response to neoadjuvant treatment is associated with better survival outcomes in patients with soft tissue sarcoma: Results of a retrospective multicenter study

BACKGROUND

Locally advanced soft tissue sarcoma (STS) management may include neoadjuvant or adjuvant treatment by radiotherapy (RT), chemotherapy (CT) or chemoradiotherapy (CRT) followed by wide surgical excision. While pathological complete response (pCR) to preoperative treatment is prognostic for survival in osteosarcomas, its significance for STS is unclear. We aimed to evaluate the prognostic significance of pCR to pre-operative treatment on 3-year disease-free survival (3y-DFS) in STS patients.

METHODS

This is an observational, retrospective, international, study of adult patients with primary non-metastatic STS of the extremities and trunk wall, any grade, diagnosed between 2008 and 2012, treated with at least neoadjuvant treatment and surgical resection and observed for a minimum of 3 years after diagnosis. The primary objective was to evaluate the effect of pCR. (≤5% viable tumor cells or ≥95% necrosis/fibrosis) on 3y-DFS. Effect on local recurrence-free survival (LRFS), distant recurrence-free survival (MFS) overall survival (OS) at 3 years was also analyzed. Statistical univariate analysis utilized chi-square independence test and odds ratio confidence interval (CI) estimate, multivariate analysis was performed using LASSO.

RESULTS

A total of 330 patients (median age 56 years old, range:19-95) treated by preoperative RT (67%), CT (15%) or CRT (18%) followed by surgery were included. pCR was achieved in 74/330 (22%) of patients, of which 56/74 (76%) had received RT. 3-yr DFS was observed in 76% of patients with pCR vs 61% without pCR (p < 0.001). Multivariate analysis showed that pCR is statistically associated with better MFS (95% CI, 1.054-3.417; p = 0.033), LRFS (95% CI, 1.226-5.916; p = 0.014), DFS (95% CI, 1.165-4.040; p = 0.015) and OS at 3 years (95% CI, 1.072-5.210; p = 0.033).

CONCLUSIONS

In a wide, heterogeneous STS population we showed that pCR to preoperative treatment is prognostic for survival.

Management of meningeal solitary fibrous tumors/hemangiopericytoma; surgery alone or surgery plus postoperative radiotherapy?

INTRODUCTION

A meningeal solitary fibrous tumor (SFT), also called hemangiopericytoma, is a rare mesenchymal malignancy. Due to anatomic constrains, even after macroscopic complete surgery with curative intent, the local relapse risk is still relatively high, thus increasing the risk of dedifferentiation and metastatic spread. This study aims to better define the role of postoperative radiotherapy (RT) in meningeal SFTs.

PATIENTS AND METHODS

A retrospective study was performed across seven sarcoma centers. Clinical information was retrieved from all adult patients with meningeal primary localized SFT treated between 1990 and 2018 with surgery alone (S) compared to those that also received postoperative RT (S + RT). Differences in treatment characteristics between subgroups were tested using independent samples t-test for continuous variables and chi-square tests for proportions. Local control (LC) and overall survival (OS) rates were calculated as time from start of treatment until progression or death from any cause. LC and OS in groups receiving S or S + RT were compared using Kaplan-Meier survival curves.

RESULTS

Among a total of 48 patients, 7 (15%) underwent S and 41 (85%) underwent S + RT. Median FU was 65 months. LC was significantly associated with treatment. LC after S at 60 months was 60% versus 90% after S + RT (p = 0.052). Furthermore, R1 resection status was significantly associated with worse LC (HR 4.08, p = 0.038). OS was predominantly associated with the mitotic count (HR 3.10, p = 0.011).

CONCLUSION

This retrospective study, investigating postoperative RT in primary localized meningeal SFT patients, suggests that combining RT to surgery in the management of this patient population may reduce the risk for local failures.

Surgical Outcome and Oncological Survival of Osteofibrous Dysplasia-Like and Classic Adamantinomas: An International Multicenter Study of 318 Cases

BACKGROUND

Osteofibrous dysplasia-like adamantinoma (OFD-AD) and classic adamantinoma (AD) are rare, neoplastic diseases with only limited data supporting current treatment protocols. We believe that our retrospective multicenter cohort study is the largest analysis of patients with adamantinoma to date. The primary purpose of this study was to describe the disease characteristics and evaluate the oncological outcomes. The secondary purpose was to identify risk factors for local recurrence after surgical treatment and propose treatment guidelines.

METHODS

Three hundred and eighteen confirmed cases of OFD-AD and AD for which primary treatment was carried out between 1985 and 2015 were submitted by 22 tertiary bone tumor centers. Proposed clinical risk factors for local recurrence such as size, type, and margins were analyzed using univariable and multivariate Cox regression analysis.

RESULTS

Of the 318 cases, 128 were OFD-AD and 190 were AD. The mean age at diagnosis was 17 years (median, 14.5 years) for OFD-AD and 32 years (median, 28 years) for AD; 53% of the patients were female. The mean tumor size in the OFD-AD and AD groups combined was 7.8 cm, measured histologically. Sixteen percent of the patients sustained a pathological fracture prior to treatment. Local recurrence was recorded in 22% of the OFD-AD cases and 24% of the AD cases. None of the recurrences in the OFD-AD group progressed to AD. Metastatic disease was found in 18% of the AD cases and fatal disease, in 11% of the AD cases. No metastatic or fatal disease was reported in the OFD-AD group. Multivariate Cox regression analysis demonstrated that uncontaminated resection margins (hazard ratio [HR] = 0.164, 95% confidence interval [CI] = 0.092 to 0.290, p < 0.001), pathological fracture (HR = 1.968, 95% CI = 1.076 to 3.600, p = 0.028), and sex (female versus male: HR = 0.535, 95% CI = 0.300 to 0.952, p = 0.033) impacted the risk of local recurrence.

CONCLUSIONS

OFD-AD and AD are parts of a disease spectrum but should be regarded as different entities. Our results support reclassification of OFD-AD into the intermediate locally aggressive category, based on the local recurrence rate of 22% and absence of metastases. In our study, metastatic disease was restricted to the AD group (an 18% rate). We advocate wide resection with uncontaminated margins including bone and involved periosteum for both OFD-AD and AD.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Abstract LB-307: Translational and mechanistic implications of osteosarcoma genomics: A TARGET report

Osteosarcoma (OS) is the most common malignant bone tumor of children and young adults. Although the optimization of combination chemotherapy has led to significantly improved prognosis, survival remains poor for patients with recurrent tumor or metastatic disease at diagnosis. The international TARGET (Therapeutically Applicable Research to Generate Effective Therapy) OS project team collected 285 clinically annotated samples (age &lt;40 years) for integrative genomics analyses. Eighty-nine cases, the discovery set, were characterized with paired tumor and normal DNA sequencing as well as profiling of transcriptomes, DNA methylation, and miRNA. An additional 196 validation cases were used for copy number analysis and targeted DNA sequencing guided by results from the discovery set. The most frequent recurrent somatic mutations cause loss of function in the tumor suppressors TP53, RB1, CDKN2A, PTEN, and NF1 as well as the chromatin remodeler ATRX. Structural rearrangements are an important mechanism of inactivation for all of these genes. In the discovery set, every case carried at least one mutation of a cell cycle regulator, with TP53 somatically altered in 87/89 cases. Analysis of TP53 mutations suggests that these are often truncal. OS genomes are strikingly complex and contain copy number aberrations (CNA) arising from aneuploidy and extensive structural rearrangements. Transcriptome analysis revealed profound remodeling of gene expression with statistically significant correlation of CNA and gene expression of 3340 genes (FDR&lt;0.001). Regions of high copy number amplification include known therapeutically relevant cancer drivers (e.g. PDGFRA, MYC, CDK4, MDM2, IGF1R, and CCNE1). In contrast, activating mutations of signal transduction genes were rare. With few exceptions (e.g. MYC amplification), mutations or CNA of individual genes were not predictive of outcome. The pattern of significant co-occurrence or mutual exclusion of frequent mutations and amplifications allowed partitioning of 240 cases into four distinct genomic groups. One of these, characterized by relatively simple genomes lacking high copy number amplification, had a more favorable outcome. Unsupervised transcriptome analysis by NMF separated the discovery set into two groups with significantly different outcomes. A pathway-based approach identified a high-risk bone differentiation signature comprised of genes highly correlated with the expression of the osteogenic transcription factors. NMF analysis of DNA methylation and miRNA data also partitioned the discovery set into two groups with the methylation groups significantly correlated with clinical outcome. Our results provide a detailed picture of the genomic complexity and heterogeneity of these tumors that suggests a model wherein most OS are initiated by TP53 loss in a proliferative cell of the osteoblast lineage. TP53 deficiency leads directly to impairment of cell cycle control, DNA repair, and terminal differentiation, a state permissive for the development of secondary CNA and epigenetic changes. The TARGET OS data are publicly available (phs000218) and of immediate relevance to future investigations of the molecular mechanisms driving osteosarcoma. Findings suggest a path forward to improved assessment of risk for individual patients and support a precision medicine approach to future clinical trial development.

Citation Format: Paul S. Meltzer, Sean Davis, Jack Zhu, Yonghong Wang, Sven Bilke, Joshua Waterfall, Robert Walker, Marbin Pineda, Yuan Jiang, Sharon Savage, Lisa Mirabello, Tsz-Kwong Man, Aaron Taylor, Monika J. Sun, Jay Wunder, Irene Andrulis, Nalan Gokgoz, Shintaro Iwata, Miki Ohira, Mark Krailo, Don Barkauskas, Lisa Teot, Timothy Triche, Silvia de Toledo, Antonio S. Petrilli, Jaime M. Guidry Auvil, Richard Gorlick, Malcolm A. Smith, Daniela Gerhard, Ching C. Lau. Translational and mechanistic implications of osteosarcoma genomics: A TARGET report [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-307.

Abstract 3875: Investigating tumor-immune interactions in adult sarcomas of the extremities

Introduction: Sarcoma is a heterogeneous group of connective tissue cancers with over 60 different subtypes. Curative treatment relies on surgical resection combined with radiation. In the event of metastasis, chemotherapy is commonly used but generally only with palliative intent. Given the heterogeneity of sarcomas, targeted therapies are limited and this has contributed to the relatively stagnant survival rates seen in the past decades.

Objective: With poorly defined cancer antigens and genetic mutations, more personalized treatments, such as immunotherapy, and in particular adoptive cell transfer therapy (ACT), may be a more viable and promising option for select sarcoma patients than currently available palliative chemotherapy. As such, our study aims to create patient specific models to investigate the interactions between tumor-infiltrating lymphocytes (TILs) and autologous tumor cells.

Methods: Over 250 tissue and blood samples from untreated sarcoma patients have been collected. The tissue samples are dissected and used for in vitro expansion of TILs or tumor cells. TIL cultures are characterized via flow cytometry and TIL responses are quantified using an IFNy ELISA. Tumor cultures are validated with RT-qPCR and dd-PCR to ensure tumor-specific mutations are retained. After characterizing and validating the cultures, autologous tumor cells and TILs are co-cultured to examine tumor-immune interactions. Outcomes of immune activity in the presence of tumor cells and tumorigenicity are evaluated to better understand the mechanisms that may be implicated in sarcoma immunotherapy.

Results: At the end of a 3-week expansion period, of the 93 primary tumor samples cultured for TILs, only 7 did not yield any TIL growth; however, the final TIL yield varied between different patient samples, ranging from 0.005 - 83M cells. Both TIL cultures expanded from different samples of the same tumor and from tumors of different patients demonstrated variable cell proportions of CD4+ and CD8+ TILs. Some cultures also contained a proportion of CD56+ cells. ELISA documented TIL responses to stimulation in all collected cultures, indicating a viable and functional population. Of the 24 primary tumor samples cultured, 17 (8 of 10 undifferentiated pleomorphic sarcomas; 7 of 10 myxofibrosarcomas; 2 of 4 osteosarcomas) generated viable tumor cell cultures as defined by the presentation of stable growth beyond passage 5.

Conclusion: Tumor cells and functional TILs can be isolated and expanded from most sarcomas; however, the methods must be optimized for each case. Further tumor culture validation by whole exome sequencing in combination with ddPCR is ongoing. A benchmark of an effective and clinically significant TIL yield will need to be better defined going forward. TILs are active in vitro and vary in population composition. Future experiments will focus on evaluating the killing capacity and tumor specificity of TILs.

Citation Format: Alice Ko, Victoria Coward, Minji Lee, Kayley Xu, Nalan Gokgoz, Brendan Dickson, Jay Wunder, Irene L. Andrulis. Investigating tumor-immune interactions in adult sarcomas of the extremities [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3875.

Long-term outcome of iliosacral resection without reconstruction for primary bone tumours

AIMS

Iliac wing (Type I) and iliosacral (Type I/IV) pelvic resections for a primary bone tumour create a large segmental defect in the pelvic ring. The management of this defect is controversial as the surgeon may choose to reconstruct it or not. When no reconstruction is undertaken, the residual ilium collapses back onto the remaining sacrum forming an iliosacral pseudarthrosis. The aim of this study was to evaluate the long-term oncological outcome, complications, and functional outcome after pelvic resection without reconstruction.

METHODS

Between 1989 and 2015, 32 patients underwent a Type I or Type I/IV pelvic resection without reconstruction for a primary bone tumour. There were 21 men and 11 women with a mean age of 35 years (15 to 85). The most common diagnosis was chondrosarcoma (50%, n = 16). Local recurrence-free, metastasis-free, and overall survival were assessed using the Kaplan-Meier method. Patient function was evaluated using the Musculoskeletal Tumour Society (MSTS) and Toronto Extremity Salvage Score (TESS).

RESULTS

At a mean follow-up of 159 months (1 to 207), 23 patients were alive without disease, one was alive with lung metastases, one was alive following local recurrence, four were dead of disease, and three had died from other causes. The overall ten-year survival was 77%. There was only one (3%) local recurrence, which occurred at 26 months. There were 18 complications in 17 patients; 13 wound healing complications/infections, three fractures, one pulmonary embolism, and one dislocation of the hip. Most complications occurred early. The mean functional scores were 21.1 (SD 8.1) for MSTS-87, 67.3 (SD 23.9) for MSTS-93 and 76.2 (SD 20.6) for TESS.

CONCLUSION

Patients requiring Type I or Type I/IV pelvic resections can expect a good oncological outcome and a high rate of local control. Complications are generally acute in nature and are easily manageable. These patients achieved a good functional outcome without the need for bony reconstruction. Cite this article: Bone Joint J 2020;102-B(6):779-787.

Fixed-hinge cemented modular implants: An effective reconstruction technique following primary distal femoral bone tumor resection. A 136-case multicenter series

BACKGROUND

Reconstruction by endoprosthesis is widespread after bone tumor resection. The design and type of fixation and of hinge remain a matter of debate. The aim of the present study was to assess survival, complications and functional results in a homogeneous series of adult patients undergoing bone defect reconstruction following distal femoral tumor resection, using a single model of fixed-hinge cemented endoprosthesis, at a minimum 5 years' follow-up.

HYPOTHESIS

The study hypotheses were that loosening and infection are the main causes of failure, and that this type of reconstruction is reliable following distal femoral resection.

PATIENTS AND METHODS

All patients aged over 17 years undergoing reconstruction using the Stanmore Mets® fixed-hinge cemented modular endoprosthesis following distal femoral resection for primary bone tumor in 4 French reference centers between 2004 and 2013 were included. Epidemiological data, MSTS functional score, clinical and radiological examination results, complications and survival with types of failure according to the Henderson classification were assessed.

RESULTS

One hundred and thirty-six patients (68 male, 68 female; mean age, 41.2 years [range, 17-77 years]) were included. Mean follow-up was 81 months [range, 61-134 months]. Thirty-two patients (38%) experienced a total 67 complications requiring surgical revision: mainly infection (n=28) or mechanical failure (n=26). Overall implant survival was 78% at 5 years. There were 30 implant failures on the Henderson classification. Mean MSTS score was 82%.

DISCUSSION

The present results are comparable to those of the literature and for other types of reconstruction. Recent meta-analyses suggest that type of hinge and of stem fixation have little effect on implant survival. International comparative studies are needed to determine the exact role of each type of reconstruction according to the patient profile.

LEVEL OF EVIDENCE

IV, multicenter retrospective series.

Extrameningeal solitary fibrous tumors-surgery alone or surgery plus perioperative radiotherapy: A retrospective study from the global solitary fibrous tumor initiative in collaboration with the Sarcoma Patients EuroNet

Background

Solitary fibrous tumor (SFT) is a rare mesenchymal malignancy. Although surgery is potentially curative, the local relapse risk is high after marginal resections. Given the lack of prospective clinical trial data, the objective of the current study was to better define the role of perioperative radiotherapy (RT) in various SFT presentations by location.

Methods

This was retrospective study performed across 7 sarcoma centers. Clinical information was retrieved from all adult patients with extrameningeal, primary, localized SFT who were treated between 1990 and 2018 with surgery alone (S) compared with those who also received perioperative RT (S+RT). Differences in treatment characteristics between subgroups were tested using analysis of variance statistics and propensity score matching. Local control and overall survival rates were calculated from the start of treatment until progression or death from any cause.

Results

Of all 549 patients, 428 (78%) underwent S, and 121 (22%) underwent S+RT. The median follow‐up was 52 months. After correction for mitotic count and surgical margins, S+RT was significantly associated with a lower risk of local progression (hazard ratio, 0.19: P = .029), an observation further confirmed by propensity score matching (P = .012); however, this association did not translate into an overall survival benefit.

Conclusions

The results from this retrospective study investigating perioperative RT in patients with primary extrameningeal SFT suggest that combining RT with surgery in the management of this patient population is significantly associated with a reduced risk of local failures, especially in patients who have less favorable resection margins and in those who have tumors with a high mitotic count.

This retrospective study of perioperative radiotherapy in patients with primary extrameningeal solitary fibrous tumors suggests that combining radiotherapy with surgery in the management of this population significantly reduces the risk of local failures, especially in patients who have less favorable resection margins or tumors with a high mitotic count.

Use of a Fascia Lata Autograft to Reconstruct a Large Triceps Tendon Defect After En-Bloc Resection of a Soft-Tissue Sarcoma: A Case Report

CASE

In this report, we present the case of a patient undergoing en-bloc resection of a large triceps soft-tissue sarcoma, requiring reconstruction of the triceps tendon including its distal insertion. We describe a surgical technique using fascia lata (FL) autograft to reconstruct the patient's extensor mechanism with long-term follow-up and functional results.

CONCLUSIONS

FL autograft is a viable option for reconstruction of large tendinous defects. It is simple and straightforward to harvest, inexpensive when compared with alternatives, with many potential applications.

Individualizing Follow-Up Strategies in High-Grade Soft Tissue Sarcoma with Flexible Parametric Competing Risk Regression Models

Currently, patients with extremity soft tissue sarcoma (eSTS) who have undergone curative resection are followed up by a heuristic approach, not covering individual patient risks. The aim of this study was to develop two flexible parametric competing risk regression models (FPCRRMs) for local recurrence (LR) and distant metastasis (DM), aiming at providing guidance on how to individually follow-up patients. Three thousand sixteen patients (1931 test, 1085 validation cohort) with high-grade eSTS were included in this retrospective, multicenter study. Histology (9 categories), grading (time-varying covariate), gender, age, tumor size, margins, (neo)adjuvant radiotherapy (RTX), and neoadjuvant chemotherapy (CTX) were used in the FPCRRMs and performance tested with Harrell-C-index. Median follow-up was 50 months (interquartile range: 23.3–95 months). Two hundred forty-two (12.5%) and 603 (31.2%) of test cohort patients developed LR and DM. Factors significantly associated with LR were gender, size, histology, neo- and adjuvant RTX, and margins. Parameters associated with DM were margins, grading, gender, size, histology, and neoadjuvant RTX. C-statistics was computed for internal (C-index for LR: 0.705, for DM: 0.723) and external cohort (C-index for LR: 0.683, for DM: 0.772). Depending on clinical, pathological, and patient-related parameters, LR- and DM-risks vary. With the present model, implemented in the updated Personalised Sarcoma Care (PERSARC)-app, more individualized prediction of LR/DM-risks is made possible.

Abstract LB-306: Long non-coding RNA NEAT1 promotes lung metastasis of soft tissue sarcoma by regulating RNA splicing pathways

Soft tissue sarcomas (STS) are malignant tumors from diverse mesenchymal tissues. About 40% STS patients develop fatal lung metastasis with a median survival of 15 months. The mechanisms driving the development of lung metastasis in sarcoma patients are poorly understood. Therefore, our lab has developed a genetically engineered mouse model (GEMM) of high-grade primary STS with conditional mutations in Kras and Trp53 (KP) where 40% of mice tumors develop lung metastasis. This KP model recapitulates human patients with Undifferentiated Pleomorphic Sarcoma (UPS), one of the most common subtypes of STS diagnosed in adults. RNA sequencing (RNA-Seq) was performed on paired primary and lung metastases in KP mouse sarcomas and determined that the expression of the long non-coding RNA (lncRNA) Neat1 is increased in lung metastases compared to paired primary tumors. Real time PCR (qPCR) in 22 paired KP mouse primary sarcomas and lung metastases further confirmed that Neat1 is significantly upregulated in some lung metastases. In addition, RNA-Seq and qPCR data from 10 pairs of human primary sarcomas and matched lung metastases also showed that NEAT1 levels are increased in lung metastases. Furthermore, NEAT1 RNA in situ hybridization (ISH) on tissue microarrays (TMAs) of human primary UPS and lung metastases determined that the expression of NEAT1 is upregulated in lung metastases. Next, CRISPR/Cas9 technology was applied to delete Neat1 in primary mouse sarcoma cells and loss of expression of Neat1 was confirmed by qPCR and northern blot in knockout (KO) clones. In addition, loss of Neat1 significantly reduced lung metastasis in vivo following tail vein injection of these modified cells into nude mice. Furthermore, RNA pull down assay with mass spectrometry analysis determined Neat1 interacting proteins, such as Khsrp, were mainly involved in RNA splicing pathways which was also shown to be dysregulated in lung metastases and Neat1 KO cells. Finally, CRISPR/Cas9 mediated knockout of Khsrp significantly reduced lung metastasis in vivo following tail vein injection of these modified cells into nude mice. Overall, these results suggest that upregulation of Neat1 promotes lung metastasis of soft tissue sarcoma through regulating RNA splicing pathways and NEAT1 is a potential target to prevent or treat lung metastasis in sarcoma patients.

Citation Format: Jianguo Huang, Eric Xu, Mohit Sachdeva, Timothy Robinson, Xiaodi Qin, Dadong Zhang, Kouros Owzar, Nalan Gokgoz, Andrew Seto, Irene Andrulis, Jay Wunder, Tomoyo Okada, Simuel Singer, Alexander Lazar, Brian Rubin, David G. Kirsch. Long non-coding RNA NEAT1 promotes lung metastasis of soft tissue sarcoma by regulating RNA splicing pathways [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-306.

Abstract 756: Whole exome sequencing identifies frequent mutations of PTPRB and KDR in secondary angiosarcoma

Angiosarcoma is an uncommon malignant vascular tumor that can occur anywhere on the body, with a predilection for the skin or soft tissues of the scalp and face.

By whole exome sequencing, we identified recurrent somatic mutations in PTPRB, which encodes an endothelial-specific phosphatase that negatively regulates angiogenesis, in three secondary angiosarcoma tumors (3/10). In addition, four tumors harbored missense variants in the KDR gene, including three germline substitutions. Neither the PTPRB nor the KDR alterations were found in the 5 primary tumors studied. Copy number analysis derived from the exome and methylation data revealed frequent MYC amplification in the majority of secondary angiosarcoma tumors (9/10).

Altogether, our data provide a comprehensive overview of genetic and epigenetic landscapes of angiosarcoma, and demonstrate that aberrant angiogenesis associated with PTPRB and KDR mutations may contribute to the pathogenesis of angiosarcoma.

Citation Format: Tenzin Gayden, Brendan C. Dickson, Hamid Nikbakht, Pierre-Olivier Fiset, Nicolas De Jay, Javad Nadaf, David L. Burk, Albert Berghuis, Rebecca Gladdy, Jay Wunder, Robert Turcotte, Jacek Majewski, Nada Jabado. Whole exome sequencing identifies frequent mutations of PTPRB and KDR in secondary angiosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 756.

Clinical characteristics of nonosteogenic, non-Ewing’s sarcoma of the bone: Experience at the Toronto Sarcoma Program

11029

Background: Non-osteogenic sarcoma of the bone is a rare entity comprising a heterogenous group of malignant tumors. Clinical characteristics and outcome data are sparse in the literature. We evaluated the characteristics and long-term outcomes of patients (pts) with this disease. Methods: Pts with non-osteogenic sarcoma of the bone treated at the Toronto Sarcoma Program from 1987-2017 were identified from our institutional sarcoma database. Patient characteristics (ie: age, gender, tumor size, histology, grade, necrosis, tumor location), treatment modality (ie: surgical management, chemotherapy, radiotherapy), and survival information were collected. Survival was estimated by Kaplan-Meier (log-rank). Multi-variate analysis (MVA) was used to evaluate characteristics for sarcoma specific survival. Results: Of 130 pts identified, 106 had non-metastatic disease with a median age of 46 (range 18-89). Male-to-female predominance was 1.5:1. Common histologies were undifferentiated pleomorphic sarcoma (UPS; 42%), leiomyosarcoma (21%), and fibrosarcoma (11%). Tumors were generally high grade (59%) and > 5 cm in size (73%). The majority of pts received chemotherapy (68%), with Cisplatin/Doxorubicin based regimens (95%). R0 resection was achieved in 85% of cases. Survival for the entire cohort, showed a median (m)DFS of 8.13 years (95%CI:2.52-18.02), and a mOS of 11.72 (95%CI:7.00-not reached [NR]). Median sarcoma specific survival was NR, however 15- and 25-year survivals were 60.4% and 52.6% respectively. MVA demonstrated axial tumor location (HR = 13.03; p = 0.005), no chemotherapy (HR = 4.50; p = 0.017) and tumor grade (G2: HR = 36.21; p = 0.012; G3: HR = 20.30; p = 0.015) as risk factors for sarcoma specific death. Tumor size > 10cm (p = 0.085) and necrosis > 90% (p = 0.082) trended towards significance. Conclusions: Non-osteogenic sarcoma of the bone is a rare tumor entity, with a predominant UPS histology. Patient outcomes are reasonable, with measurable long-term survival. Axial tumor location, absence of chemotherapy, and high-grade disease predict for worse survival outcome. Further evaluation with larger data series is warranted to more fully understand this disease.

Intracellular cholesterol biosynthesis in enchondroma and chondrosarcoma

Enchondroma and chondrosarcoma are the most common benign and malignant cartilaginous neoplasms. Mutations in isocitrate dehydrogenase 1 and 2 (IDH1/2) are present in the majority of these tumors. We performed RNA-seq analysis on chondrocytes from Col2a1Cre;Idh1LSL/+ animals and found that genes implied in cholesterol synthesis pathway were significantly upregulated in the mutant chondrocytes. We examined the phenotypic effect of inhibiting intracellular cholesterol biosynthesis on enchondroma formation by conditionally deleting SCAP (sterol regulatory element-binding protein cleavage-activating protein), a protein activating intracellular cholesterol synthesis, in IDH1 mutant mice. We found fewer enchondromas in animals lacking SCAP. Furthermore, in chondrosarcomas, pharmacological inhibition of intracellular cholesterol synthesis significantly reduced chondrosarcoma cell viability in vitro and suppressed tumor growth in vivo. Taken together, these data suggest that intracellular cholesterol synthesis is a potential therapeutic target for enchondromas and chondrosarcomas.

Abstract 516: Long noncoding RNA NEAT1 promotes lung metastasis of soft tissue sarcoma

Soft tissue sarcomas (STS) are malignant tumors from diverse mesenchymal tissues. About 40% STS patients develop fatal lung metastasis with a median survival of 15 months. The mechanisms driving the development of lung metastasis in sarcoma patients are poorly understood. Therefore, our lab has developed a genetically engineered mouse model (GEMM) of high-grade primary STS with conditional mutations in Kras and Trp53 (KP) where 40% of mice tumors develop lung metastasis. This KP model recapitulates human patients with Undifferentiated Pleomorphic Sarcoma (UPS), one of the most common subtypes of STS diagnosed in adults. RNA sequencing (RNA-Seq) was performed on paired primary and lung metastases in KP mouse sarcomas and determined that the expression of the long non-coding RNA (lncRNA) Neat1 is increased in lung metastases compared to paired primary tumors. Real time PCR (qPCR) in 22 paired KP mouse primary sarcomas and lung metastases further confirmed that Neat1 is significantly upregulated in lung metastases. In addition, RNA-Seq data from 5 pairs of human primary sarcomas and matched lung metastases also showed that NEAT1 levels are increased in lung metastases. Furthermore, NEAT1 RNA in situ hybridization (ISH) on tissue microarrays (TMAs) of human primary UPS and lung metastases determined that the expression of NEAT1 is upregulated in lung metastases. Next, CRISPR/Cas9 technology was applied to delete Neat1 in primary mouse sarcoma cells and loss of expression of Neat1 was confirmed by qPCR and northern blot in knockout (KO) clones. In addition, loss of Neat1 significantly reduced lung metastasis in vivo following tail vein injection of these modified cells into nude mice. To further test that loss of Neat1 reduces lung metastasis in primary sarcoma mouse model, primary tumors with Neat1 deletion are generated in GEMMs using in vivo CRISPR/Cas9 technology and KrasLSL-G12D/+; Trp53Flox/Flox; Neat1-/- (KPN) mouse model. Finally, RNA-Seq and capture hybridization analysis of RNA targets (CHART) are performed to determine mechanisms by which Neat1 regulates lung metastasis. Overall, these results suggest that upregulation of Neat1 promotes lung metastasis of soft tissue sarcoma and NEAT1 is a potential target to prevent or treat lung metastasis in sarcoma patients.

Citation Format: Jianguo Huang, Eric Xu, Mohit Sachdeva, Timothy Robinson, Xiaodi Qin, Dadong Zhang, Kouros Owzar, Nalan Gokgoz, Andrew Seto, Irene Andrulis, Jay Wunder, Tomoyo Okada, Samuel Singer, Alexander Lazar, Brian Rubin, David G. Kirsch. Long noncoding RNA NEAT1 promotes lung metastasis of soft tissue sarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 516.

Abstract A04: Molecular characterization of undifferentiated pleomorphic sarcomas

Objective: Undifferentiated pleomorphic sarcomas (UPS) are high-grade soft-tissue sarcomas (STS) with no apparent line of differentiation. Despite overall gains in the management of STS, progress in therapies based on molecular targets and understanding the unknown genetic diversity is needed, especially in UPS where response to therapy is limited. Using integrated multi-omic analysis, we aim to characterize UPS for recurrent genetic mutations, altered pathways, and the mutational spectrum. These insights into UPS may enable robust classification, identify prognostic markers, and lead to novel treatment approaches.

Methods: Clinically well-annotated cases of UPS with matched blood specimens were retrieved from the Sarcoma Tumor Bank at Mount Sinai Hospital, Toronto. Using current World Health Organization histopathologic classification, reevaluated cases were subjected to whole-genome (WGS) or whole-exome sequencing (WES) and RNA sequencing (RNA-seq). Cell lines and/or mouse xenografts were established from some of the UPS tumors. The goal of this study was to integrate annotated somatic mutations, expressed transcripts, mRNA fusions, structural rearrangements, and copy number aberrations to detect recurrent molecular features in UPS.

Results: At present, 43 UPS tumor, 8 matched metastatic samples, 6 mouse xenografts, and 4 cell lines have been sequenced by WGS or WES and RNA-seq. Among the 34 cases analyzed by WES, known cancer genes TP53, LRP1B, ATRX, and RB1 are found to recurrently contain somatic variants. Among these genes, nonsilent somatic variants were found in 18/34 tumors. The somatic variant burden among the WES tumors is approximately 5 muts/Mb. Two UPS cases were hypermutated with a somatic variant burden &gt;10 muts/Mb. In examining the base changes in the hypermutated cases, the two display a C&gt;A bias, in which the 5' and 3' bases flanking the C&gt;A alterations in the hypermutated cases have a distinct pattern (TpCpN, CpCpA) that differ from the other samples. These somatic C&gt;A biases in their trinucleotide context were not detected in &gt;10K tumor cases across 33 cancer types sequenced by TCGA. An RB1 and ATXN10 fusion transcript that lacks the RB1 tumor-suppressing domain was confirmed in one case, while the derived cell line also expressed the RB1-ATXN10 fusion. The cell lines and xenograft models retained 8-71% of their matched tumors' somatic variants. The metastatic samples contained between 13-63% of the somatic variants also identified in their matched primary tumors, among the 4 WES metastatic samples analyzed thus far.

Conclusion: Initial analyzes of UPS tumors has identified recurrently mutated cancer-related genes and a unique pattern of C&gt;A bias not previously seen. Ongoing multi-omic analysis, integrating the RNA-seq with the somatic alterations, of UPS tumors may reveal further genomic events that may aid in stratification of UPS, understand the drivers of the disease, identify actionable targets, and realize novel therapeutics.

Citation Format: Andrew Seto, Nalan Gokgoz, Qingxia Wei, Yael Babichev, Brendan C. Dickson, Benjamin Alman, Rebecca A. Gladdy, Adam Shlien, Jay Wunder, Irene L. Andrulis. Molecular characterization of undifferentiated pleomorphic sarcomas [abstract]. In: Proceedings of the AACR Conference on Advances in Sarcomas: From Basic Science to Clinical Translation; May 16-19, 2017; Philadelphia, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(2_Suppl):Abstract nr A04.

The driver landscape of sporadic chordoma

Chordoma is a malignant, often incurable bone tumour showing notochordal differentiation. Here, we defined the somatic driver landscape of 104 cases of sporadic chordoma. We reveal somatic duplications of the notochordal transcription factor brachyury (T) in up to 27% of cases. These variants recapitulate the rearrangement architecture of the pathogenic germline duplications of T that underlie familial chordoma. In addition, we find potentially clinically actionable PI3K signalling mutations in 16% of cases. Intriguingly, one of the most frequently altered genes, mutated exclusively by inactivating mutation, was LYST (10%), which may represent a novel cancer gene in chordoma.Chordoma is a rare often incurable malignant bone tumour. Here, the authors investigate driver mutations of sporadic chordoma in 104 cases, revealing duplications in notochordal transcription factor brachyury (T), PI3K signalling mutations, and mutations in LYST, a potential novel cancer gene in chordoma.

Abstract 319: Cholesterol inhibition reduces Hh mediated chondrosarcoma

Constitutive activation of Hh signaling is a common occurrence in chondrosarcoma(CSA). Gene profiling analysis showed that Gli transcription regulates genes that govern cholesterol homeostasis, which alters cholesterol accumulation in chondrocytes; a higher level of Gli-mediated transcription results in accumulation of intracellular cholesterol. Here we determined if targeting cholesterol-processing genes downstream of Hh signalling could be used as a novel treatment approach. With institutional review board approval, human CSA samples were obtained fresh from surgery. For in vitro studies, CSA explants of 2mmx2mm x2 mm cubic in size establihed as organ cultures. For in vivo studies, one million CSA cells were subcutanously injected into NSG mice. Cells from five CSAs were treated both in vitro and in vivo with a hedgehog inhibitor, Cur61414, a cholesterol inhibitor, Lovastatin, or both. In vitro, CSA explants were treated for 48 hrs at concentration of 20 μM of each drug. In vivo, mice were treated with 4.5mg/kg/day of Cur61414, Lovastatin, or both by intraperitoneal injection for 4 wks. At the end of treatment, the explants or xenografts were harvested and processed for further analysis. RT-PCR was used to meausre the expression of Hh and cholesterol target genes. Tumor size was meausred from the xenografts. Blockade of Hh signaling significantly decreased Gli1 gene expression by 30%, increased 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) expression for more than 300% indicating decreased intracellular cholesterol. Treatment with the cholesterol inhibitor Lovastatin increased expression of HMGCR for more than 500%. The combination of Hh and cholesterol blockage resulted in increased expression of HMGCR for more than 3400%. Analysis of chondrosarcoma xenografts in vivo showed a significnat decrease in tumor size with Lovastatin (32% decline), 3 folds reducation of Brdu(+) cells, and 2.4 fold increase of Caspase-3 + cells, treatment with Cur 61414 reduced the tumor growth by 5% with no significant reduction of Brdu(+) cells but 2.6 fold increase of Caspase-3 (+) cells . The combination treatment of lovastatin and Cur61414 on xenografts resulted in a significnat decrease in tumor size (32% decline), 3 fold reduction of Brdu (+) cells, but no significant changes of Caspase-3 (+) cells . These data suggest that cholesterol functions downstream of Hh signaling pathway in CSA. The more effective reduction in tumor growth with cholesterol inhibition compared to Hh blockade suggests cholesterol blockade is an effective therapeutic approach.

Citation Format: Qingxia Wei, Eyal Ramu, Mushriq AL-Jazrawe, Raymond Poon, Jay Wunder, Benjamin Alman. Cholesterol inhibition reduces Hh mediated chondrosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 319. doi:10.1158/1538-7445.AM2017-319

Abstract 4741: Biomarker significance of plasma and tumor miR-21, miR-221, and miR-106a in pediatric osteosarcoma

Osteosarcoma is the most common malignant bone tumor in children and young adults. Despite the use of surgery and multi-agent chemotherapy, osteosarcoma patients who respond poorly towards chemotherapy or develop relapses have a dismal outcome. Identification of biomarkers for active disease may help to monitor tumor burden, detect early relapses, and predict prognosis in these patients, so that they can be treated as early as possible to improve their survival. In this study, we examined if circulating microRNAs (miRNAs) can be used as biomarkers in osteosarcoma patients. We performed genome-wide miRNA profiling on a discovery cohort of OS plasma samples (n=32) collected from the Texas Children’s Hospital. A total of 56 miRNAs were upregulated and 164 miRNAs were downregulated in osteosarcoma samples when compared to normal plasma samples (n=8). miRNA-21, miR-221 and miRNA-106a were selected for further validation based on their known biological importance. We showed that all three circulating miRNAs were expressed significantly higher in OS samples (n=29) than normal samples (n=17) in an independent cohort obtained from the Children’s Oncology Group. Furthermore, we demonstrated that miR-21 was expressed significantly higher in osteosarcoma tumors (n=89) compared with normal bone controls. More importantly, lower expressions of miR-21 and miR-221, but not miR-106a, significantly correlated with a poor outcome. In conclusion, our results indicate that miR-21, miR-221 and miR-106a are elevated in the circulation of osteosarcoma patients, whereas tumor expressions of miR-21 and miR-221 are prognostically significant. Further investigation of the miRNAs may lead to a better prognostic method and potential miRNA therapeutics for osteosarcoma.

Citation Format: Manjula Nakka, Wendy Allen-Rhoades, Yiting Li, Aaron Kelly, Jianhe Shen, Aaron Taylor, Donald A. Barkauskas, Jason Yustein, Irene Andrulis, Jay Wunder, Richard Gorlick, Paul Meltzer, Ching Lau, Tsz-Kwong Man. Biomarker significance of plasma and tumor miR-21, miR-221, and miR-106a in pediatric osteosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4741. doi:10.1158/1538-7445.AM2017-4741

Influence of chemotherapy combined with radiotherapy on the time-to-development of radiation-induced sarcomas: A multicenter, retrospective analysis

11046

Background: An increasing number and proportion of cancer patients with apparently localised disease are treated with chemotherapy and radiation therapy in contemporary oncology practice. In a pilot study of radiation-induced sarcoma (RIS) patients, we demonstrated that chemotherapy was associated with a reduced time to development of RIS. We now present an international multi-centre collaborative study to validate this association. Methods: This was a retrospective cohort study of RIS cases across five large international sarcoma centres between the 1st January, 2000 to 31st December, 2014. The primary endpoint was time to development of RIS, defined as the date of diagnosis of the first malignancy to date of the RIS diagnosis. We also assessed the relationship between chemotherapy, patient and cancer characteristics, and time to RIS. Results: We identified 419 patients with RIS, who were predominantly diagnosed with their first malignancy at adulthood. The median interval from the index cancer to development of RIS for the entire cohort was 11 years (range 1-64). Chemotherapy for the first malignancy was associated with a shorter time to RIS development (HR 1·37; 95% CI: 1·08-1·72; P = 0·009). In the multi-variable model, older age (HR 2·11; CI 1·83-2·43; P < 0·001) and chemotherapy for the first malignancy (HR 1·61; CI 1·26-2·05; P < 0·001) were independently associated with a shorter time to RIS. Anthracyclines and alkylating agents significantly contribute to the effect. Conclusions: This study confirms an association between chemotherapy given for the first malignancy and a shorter time to development of a RIS. Our data highlights the importance of vigilance in surveillance for RIS after chemotherapy and radiation therapy, particularly in younger patients who also have a longer potential time to develop a second malignancy.

Immunoprofiling in alveolar soft part sarcoma

11059

Background: Alveolar Soft Part Sarcoma (ASPS) is a distinctive tumor characterized by a canonical ASPL-TFE3 fusion. Treatment options are limited. We assessed tumor immune cell infiltrates, and correlated this with patients receiving PD-1 blockade. Methods: A retrospective institutional review was performed for 18 cases of ASPS. Immunohistochemistry was performed on paraffin-embedded tissue (PET) for T-lymphocyte markers (CD3/CD4/CD8), and PD-1/PD-L1 (Ventana). Expression was quantified by standard methods: (total cells per high power field: score; 0:0; 1-10:1; 11-50:2; 50-99:3; 100:4). Select cases underwent DNA sequencing analysis using whole exome (WES, > 80X, n = 4) and genome (WGS, > 30X, n = 1) sequencing. Indel analysis was conducted via mutect2 ( > 5% variant allele frequency) and mutational signature was performed using deconstructSigs. Results: The median age was 27 (15-54). Disease status at diagnosis was: 44% localized; 56% metastatic. The median overall survival was 17 yrs (2.9-31). Four patients (pts) received immunotherapy with PD-1 blockade with 1 complete response (CR), 2 durable partial responses (PR) and 1 stable disease (SD). PET was available in 12 cases. PD-1/PD-L1 expression (≥1) was seen in 50% and 17%, respectively. Composite CD3, CD4 and CD8 infiltration were 2, 1, and 1, respectively. Patients with CR/PR to PD-1 blockade (n = 3) had no clear correlation with PD-1, PD-L1 or lymphocyte markers. Exomic characterization (n = 4) demonstrated no clear excess mutation burden compared to Ewing sarcoma (5.7 vs 6.4 mut/MB). Mutational signatures via COSMIC were identified in the mismatch repair (MMR) pathway in 2 of 4 cases (Pt A: Signature (S) 26; pt B: S6 and S15). Pt B also underwent WGS which confirmed a COSMIC signature in the MMR pathway. Indel analysis did not confirm aberrations in standard MMR or polymerase genes. Conclusions: Preliminary findings suggest activity with PD-1 blockade in ASPS; however, this does not appear to correlate with tumour-infiltrating T lymphocytes. Genomic analysis suggests an MMR signature may account for these responses, but standard MMR aberrations were not identified. Further validation is underway.

Identification of CD146 as a marker enriched for tumor-propagating capacity reveals targetable pathways in primary human sarcoma

Tumor-propagating cells (TPCs) are believed to drive cancer initiation, progression and recurrence. These cells are characterized by enhanced tumorigenicity and self-renewal. The ability to identify such cells in primary human sarcomas relies on the dye exclusion ability of tumor side population (SP) cells. Here, we performed a high-throughput cell surface antigen screen and found that CD146 is enriched in the SP population. In vivo serial transplantation assays showed that CD146+ cells are highly tumorigenic, capable of self-renewal and thus enriches for the TPC population. In addition, depletion of SP cells from the CD146+ population show that CD146+ cells and SP cells are a distinct and overlapping TPC populations. Gene expression profiling of CD146+ and SP cells revealed multiple pathways commonly upregulated in both of these populations. Inhibition of one of these upregulated pathways, Notch signaling, significantly reduced tumor growth and self-renewal. Our data demonstrate that CD146 is an effective cell surface marker for enriching TPCs in primary human sarcomas. Targeting differentially activated pathways in TPCs may provide new therapeutic strategies for treating sarcoma.

The inter-rater reliability of the diagnosis of surgical site infection in the context of a clinical trial

OBJECTIVES

The diagnosis of surgical site infection following endoprosthetic reconstruction for bone tumours is frequently a subjective diagnosis. Large clinical trials use blinded Central Adjudication Committees (CACs) to minimise the variability and bias associated with assessing a clinical outcome. The aim of this study was to determine the level of inter-rater and intra-rater agreement in the diagnosis of surgical site infection in the context of a clinical trial.

MATERIALS AND METHODS

The Prophylactic Antibiotic Regimens in Tumour Surgery (PARITY) trial CAC adjudicated 29 non-PARITY cases of lower extremity endoprosthetic reconstruction. The CAC members classified each case according to the Centers for Disease Control (CDC) criteria for surgical site infection (superficial, deep, or organ space). Combinatorial analysis was used to calculate the smallest CAC panel size required to maximise agreement. A final meeting was held to establish a consensus.

RESULTS

Full or near consensus was reached in 20 of the 29 cases. The Fleiss kappa value was calculated as 0.44 (95% confidence interval (CI) 0.35 to 0.53), or moderate agreement. The greatest statistical agreement was observed in the outcome of no infection, 0.61 (95% CI 0.49 to 0.72, substantial agreement). Panelists reached a full consensus in 12 of 29 cases and near consensus in five of 29 cases when CDC criteria were used (superficial, deep or organ space). A stable maximum Fleiss kappa of 0.46 (95% CI 0.50 to 0.35) at CAC sizes greater than three members was obtained.

CONCLUSIONS

There is substantial agreement among the members of the PARITY CAC regarding the presence or absence of surgical site infection. Agreement on the level of infection, however, is more challenging. Additional clinical information routinely collected by the prospective PARITY trial may improve the discriminatory capacity of the CAC in the parent study for the diagnosis of infection.Cite this article: J. Nuttall, N. Evaniew, P. Thornley, A. Griffin, B. Deheshi, T. O'Shea, J. Wunder, P. Ferguson, R. L. Randall, R. Turcotte, P. Schneider, P. McKay, M. Bhandari, M. Ghert. The inter-rater reliability of the diagnosis of surgical site infection in the context of a clinical trial. Bone Joint Res 2016;5:347-352. DOI: 10.1302/2046-3758.58.BJR-2016-0036.R1.

Sampling modality influences the predictive value of grading in adult soft tissue extremity sarcomas

CONTEXT

Histologic grade is one of the best predictors of outcome in adult soft tissue sarcomas. Current grading systems were validated on resection specimens; however, there has been a trend toward the use of biopsies to diagnosis these tumors.

OBJECTIVES

To determine whether the grade of an extremity soft tissue sarcoma determined on tissue obtained by either core needle biopsy or incisional biopsy is predictive of metastasis- or disease-free survival, and whether either sampling modality is superior.

DESIGN

One hundred three core needle biopsies and 107 incisional biopsies of nonmetastatic spindle cell sarcomas of the extremities were retrieved from the archives. All cases had a minimum 2-year follow-up. Patient data and outcome and tumor characteristics were recorded. Tumors were reviewed and evaluated using the French Federation of Cancer Centers Sarcoma Group grading system. Kaplan-Meier survival curves were generated to correlate tumor grade with metastasis- and disease-free survival for both groups.

RESULTS

Patient and tumor characteristics were similar between groups except that more tumors were grade 3 and superficial in the incisional biopsy group. Grade determined on core needle biopsy was not predictive of either metastasis-free survival (P = .59) or disease-free survival (P = .50). In contrast, grade determined on incisional biopsy was predictive of both metastasis-free survival (P < .001) and disease-free survival (P = .001).

CONCLUSIONS

Biopsy, particularly core needle biopsy, represents a convenient diagnostic tool, particularly in the context of neoadjuvant therapy. However, based on these results incisional biopsy is recommended if grading is to be used to predict prognosis in spindle cell soft tissue sarcomas of the extremities.

MRI characteristics of nodular fasciitis of the musculoskeletal system

OBJECTIVE

To evaluate MRI imaging appearances of nodular fasciitis in a pathologic-proven series of 29 patients.

MATERIALS AND METHODS

Review of the orthopedic oncology and pathology databases yielded 51 cases of histologically proven nodular fasciitis. MR imaging was available in 29 patients. Three musculoskeletal radiologists retrospectively reviewed all cases in consensus. Imaging features evaluated included location in the body, size, compartmental localization, relationship to fascia, signal characteristics, enhancement pattern, transcompartmental extension, and osseous and intra-articular involvement.

RESULTS

There were 15 male and 14 female patients. Mean age was 33 years (range, 16-59 years). Lesions ranged in size from 1.6 to 9 cm with 84 % of lesions measuring less than 4 cm. Twenty-three lesions were located in the upper arm or shoulder girdle. Nine lesions were subcutaneous in location, nine were intra-muscular, and 11 were inter-muscular. Lesions were consistently ovoid in shape with broad fascial contact. They exhibited internal homogenous low T1 and heterogeneous intermediate T2 signal with surrounding edema and slightly inhomogeneous enhancement. Twelve lesions exhibited central non-enhancing areas. Trans-compartmental spread was demonstrated in nine lesions. Osseous changes were seen in five cases and included extrinsic cortical saucerization, medullary edema, and transcortical osseous invasion. Two lesions demonstrated intra-articular extension.

CONCLUSIONS

MR imaging features of nodular fasciitis are generally non-specific and can be mistaken for a soft tissue sarcoma. This series, the largest MRI series of musculoskeletal cases in the literature, confirms the predilection of nodular fasciitis for the upper extremity in young adults but also demonstrates that aggressive imaging features such as transcompartmental spread, and osseous and intra-articular involvement may be seen in association with this benign soft tissue lesion.

Prophylactic antibiotic regimens in tumor surgery (PARITY) survey

BACKGROUND

Deep infection following endoprosthetic limb reconstruction for sarcoma of the long bones is a devastating complication occurring in 15% of sarcoma patients. Optimizing infection protocols and conducting definitive surgical trials are critical to improving outcomes. In this study, the PARITY (Prophylactic Antibiotic Regimens in Tumor Surgery) investigators aimed to examine surgeon preferences in antibiotic prophylaxis and perceptions about current evidence, as well as to ascertain interest in resolving uncertainty in the evidence with clinical trials.

METHODS

We used a cross-sectional survey to examine current practice in the prescription of prophylactic antibiotics in Musculoskeletal Tumor Surgery. The survey was approved by our institution's Ethics Board and emailed to all Active Members of the Musculoskeletal Tumor Society (MSTS) and Canadian Orthopaedic Oncology Society (CANOOS). Survey answers were collected using an anonymous online survey tool.

RESULTS

Of the 96 surgeons who received the questionnaire, 72 responded (75% response rate (% CI: 65.5, 82.5%)). While almost all respondents agreed antibiotic regimens were important in reducing the risk of infection, respondents varied considerably in their choices of antibiotic regimens and dosages. Although 73% (95% CI: 61, 82%) of respondents prescribe a first generation cephalosporin, 25% favor additional coverage with an aminoglycoside and/or Vancomycin. Of those who prescribe a cephalosporin, 33% prescribe a dosage of one gram for all patients and the reminder prescribe up to 2 grams based on body weight. One in three surgeons (95% CI: 25, 48%) believes antibiotics could be discontinued after 24 hours but 40% (95% CI: 30, 53%) continue antibiotics until the suction drain is removed. Given the ongoing uncertainty in evidence to guide best practices, 90% (95% CI: 81, 95%) of respondents agreed that they would change their practice if a large randomized controlled trial showed clear benefit of an antibiotic drug regimen different from what they are currently using. Further support for a clinical trial was observed by an overwhelming surgeon interest (87%; 95% CI: 77, 93%) in participating in a multi-center randomized controlled study.

CONCLUSION

The current lack of guidelines for the prescription of prophylactic antibiotics in Musculoskeletal Tumor Surgery has left Orthopaedic Oncologists with varying opinions and practices. The lack of current evidence and strong surgeon support for participating in a definitive study provides strong rationale for clinical trials.

Prophylactic antibiotic regimens in tumour surgery (PARITY): protocol for a multicentre randomised controlled study

INTRODUCTION

Limb salvage with endoprosthetic reconstruction is the standard of care for the management of lower-extremity bone tumours in skeletally mature patients. The risk of deep postoperative infection in these procedures is high and the outcomes can be devastating. The most effective prophylactic antibiotic regimen remains unknown, and current clinical practice is highly varied. This trial will evaluate the effect of varying postoperative prophylactic antibiotic regimens on the incidence of deep infection following surgical excision and endoprosthetic reconstruction of lower-extremity bone tumours.

METHODS AND ANALYSIS

This is a multicentre, blinded, randomised controlled trial, using a parallel two-arm design. 920 patients 15 years of age or older from 12 tertiary care centres across Canada and the USA who are undergoing surgical excision and endoprosthetic reconstruction of a primary bone tumour will receive either short (24 h) or long (5 days) duration postoperative antibiotics. Exclusion criteria include prior surgery or infection within the planned operative field, known colonisation with methicillin-resistant Staphylococcus aureus or vancomycin-resistant Enterococcus at enrolment, or allergy to the study antibiotics. The primary outcome will be rates of deep postoperative infections in each arm. Secondary outcomes will include type and frequency of antibiotic-related adverse events, patient functional outcomes and quality-of-life scores, reoperation and mortality. Randomisation will be blocked, with block sizes known only to the methods centre responsible for randomisation, and stratified by location of tumour and study centre. Patients, care givers and a Central Adjudication Committee will be blinded to treatment allocation. The analysis to compare groups will be performed using Cox regression and log-rank tests to compare survival functions at α=0.05.

ETHICS AND DISSEMINATION

This study has ethics approval from the McMaster University/Hamilton Health Sciences Research Ethics Board (REB# 12-009). Successful completion will significantly impact on clinical practice and enhance patients' lives. More broadly, this trial will develop a network of collaboration from which further high-quality trials in Orthopaedic Oncology will follow.

Myxoid\round cell liposarcoma (MRCLS) revisited: an analysis of 418 primarily managed cases

BACKGROUND

Objectives of this study were to evaluate oncologic outcomes and to provide guidelines for the management of primary myxoid (MLS) and round cell liposarcoma (RCLS).

METHODS

A multicenter, retrospective study of 418 cases of MRCLS primarily managed by Canadian multidisciplinary sarcoma teams.

RESULTS

Study included 418 cases (MLS: 311 patients and RCLS: 107; >5% round cell) with a median age of 45 years and a median follow-up of 5.2 years. Median tumor size was 10 cm, and 81% were deep and 90% were in lower limb. The majority of patients underwent surgical resection and radiotherapy, with a small percentage (6%) receiving chemotherapy. The overall 10-year local control rate was 93% with no differences between MLS and RCLS. Radiotherapy was significant in preventing local relapse and reducing tumor diameter (median=18%) and improving microscopic margin status, but did not impact survival. Radiotherapy and the margin status were independent predictors of local recurrence. The 5- and 10-year metastatic-free survivals were 84 and 77% respectively for MLS and 69 and 46% for RCLS. The initial site of metastasis was found in multiple locations (34%) and bone involvement was frequent (40%) with predilection for spine (79%). Round cell percent (>5%) and tumor diameter (>10 cm) correlated with increased risk for metastasis and death.

CONCLUSIONS

MLS and RCLS showed different metastatic risk but equally good local control. Radiotherapy was effective in preventing local recurrence and should be delivered as neoadjuvant. New staging strategies are to be defined to account for the unusual metastatic pattern.

Clinical outcome of children and adults with localized Ewing sarcoma: impact of chemotherapy dose and timing of local therapy

BACKGROUND

As Ewing sarcoma (EWS) can affect children and adults, these patients can be treated at either a pediatric or an adult institution. This study investigated whether differences in therapeutic strategy undertaken in pediatric and adult specialty sarcoma centers correlated with clinical outcome.

METHODS

Data from patients with localized EWS treated between 1990 and 2005 at tertiary care pediatric and adult institutions were reviewed.

RESULTS

Fifty-three patients (24 adult and 29 pediatric) were treated. Pediatric patients received a median of 16 cycles of chemotherapy comprised of doxorubicin, vincristine, cyclophosphamide, ifosfamide, and etoposide. Adult patients received a median of 10 cycles of treatment, and a significantly lower total cumulative dose of ifosfamide and cyclophosphamide (P < .0001). There was no difference noted with regard to the total dose of doxorubicin, or in the type of local therapy offered (surgery or radiotherapy, vs both). However, local therapy occurred earlier in pediatric patients compared with adults (3.7 months vs 7.4 months; P = .0003). The 3-year event-free survival (EFS) rate in pediatric and adult patients was 70% +/- 9% and 43% +/- 13% (P = 0.1), respectively. The 3-year overall survival rate was 81% +/- 7.7% and 59% +/- 12% (P = .02) for pediatric and adult patients, respectively. Factors found to be significantly associated with EFS on univariate analysis included pelvic site, cyclophosphamide dose, and time to local therapy. On multivariate analysis, only pelvic disease (hazard ratio [HR] 4.26; P = .018) and time to local therapy (HR, 1.19; P = .002) were found to be significant.

CONCLUSIONS

Adults with localized EWS have an inferior outcome compared with pediatric patients. This difference may be related to lower doses of alkylating agents and the timing of local therapy.

Function and health status outcomes following soft tissue reconstruction for limb preservation in extremity soft tissue sarcoma

BACKGROUND

While advances in reconstructive surgery have facilitated limb preservation in extremity soft tissue sarcoma (ESTS), limited information exists as to the functional outcome of patients with these reconstructed extremities. The primary objective of this study is to evaluate the impact of flap reconstruction on postoperative function and health status in patients undergoing limb-salvage surgery for ESTS.

METHODS

Clinical and outcome data for eligible patients were extracted from a prospectively maintained database of sarcoma patients. Four outcome measures were used to assess three domains of function (impairments, activity limitations, and participation restrictions), and health status. The effect of soft tissue reconstruction on function and health status at 1-2-year follow-up was analyzed using univariate and multivariate regression.

RESULTS

Two hundred and forty-seven patients met eligibility criteria, including 56 patients receiving flap reconstruction and 191 patients treated with primary closure. Patients receiving flaps had larger (9.8 versus 7.1 cm; P = 0.003), higher-grade (93% versus 72%; P = 0.001) tumors, and more frequently received radiotherapy (89% versus 72%; P = 0.007), and bone (20% versus 4%; P = 0.001) and motor nerve resection (21% versus 10%; P = 0.032). Flap reconstruction was associated with more postoperative impairments [Musculoskeletal Tumor Society (MSTS) score 30.4 versus 32.2; P = 0.004] and activity limitations [Toronto Extremity Salvage Score (TESS) score 83.3 versus 89.5; P = 0.0132] on univariate analyses, but did not significantly predict postoperative function or health status outcomes on multivariate analyses.

CONCLUSIONS

Flap reconstruction was not an independent predictor of function and health status outcomes in patients with ESTS. However, ESTS patients receiving flaps had other clinical features placing them at risk for worse postoperative outcomes.