A systematic review of optimal treatment strategies for localized Ewing's sarcoma of bone after neo-adjuvant chemotherapy

Druggable upregulated proteins in EWS-FLI-driven Ewing sarcoma as emerging new therapeutic targets

Ewing sarcoma (ES) is a highly aggressive soft tissue tumor that primarily affects the long bones of children and young adults. It is distinguished by a characteristic chromosomal translocation between the Ewing sarcoma breakpoint region 1 (EWS) gene and the erythroblast transformation-specific (ETS) family of genes, most commonly resulting in the EWS-friend leukemia integration 1 (EWS-FLI1) fusion gene. This translocation is observed in approximately 80%-85% of ES cases. This fusion gene encodes a non-physiological chimeric fusion protein that plays a central role in tumorigenesis by interacting with numerous partner proteins. Several studies have demonstrated the tumorigenic potential of the EWS-FLI1 protein when transfected into non-cancer cell lines. However, targeting EWS-FLI1 directly remains a significant challenge, as no drug to date has been reported to bind to and inhibit its activity effectively. An alternative therapeutic strategy involves targeting key overexpressed protein complexes implicated in ES tumorigenesis, many of which may be downstream interacting partners of EWS-FLI1. This review explores emerging protein targets as potential therapeutic avenues in ES treatment.

Relationship between surgical compliance and survival outcome in patients with Ewing sarcoma

BACKGROUND

The impact of surgical compliance on survival outcomes in patients with Ewing sarcoma (ES) is unclear, so this study was performed to explore the association between them.

METHODS

We used the SEER*Stat software (version 8.3.6.1) to extract information on ES patients from the SEER database. Patients were divided into two groups based on their adherence to surgical recommendations: the surgical compliance group and the surgical noncompliance group. Categorical variables were expressed as percentages. Multivariate logistic regression and Chi-square test were used to explore variables related to surgical compliance. Univariate Cox regression analysis was used to initially select potential prognostic factors, and then the factors selected in the univariate Cox regression analysis were further analyzed in a multivariate Cox proportional risk model to ultimately determine the risk prognostic factors significantly related to the survival of patients with ES.

RESULTS

Multiple logistic regression analysis suggested that adults (OR = 0.373, 95% confidence interval (CI): 0.164-0.849), Grade IV (OR = 0.373, 95% CI: 0.164-0.849), and unmarried patients (OR = 0.568, 95% CI: 0.339-0.954) were more inclined to accept surgery recommendations, while patients from 2001 to 2010 were less compliant with surgery. Multifactorial Cox regression analysis suggested that surgical compliance was an independent prognostic factor for patients with ES. Through the Kaplan-Meier survival curves, we could clearly observe that the overall survival was higher in the surgical compliance group than in the surgical noncompliance group. Furthermore, subgroup analysis also reached similar conclusions.

CONCLUSION

In this study, we found that surgical compliance was an independent predictor of patient prognosis. Furthermore, we found that age, tumor grade, year of diagnosis, and marital status may be related to surgical compliance.

Ewing Sarcoma in the Pediatric Population: Predictors of Survival Within the United States

INTRODUCTION

Bone and joint tumors are the third most common cause of pediatric cancer-related deaths in the United States. Although there have been improvements in survival rates among pediatric cancer patients over the past few decades, bone and joint cancers remain the exception. Considering current clinical trials involving novel targeted therapies, the establishment of updated mortality rates and predictors of survival for this cancer would be prudent. This investigation sought to determine updated 5-year survival rates and predictors of survival among pediatric Ewing sarcoma (ES) of bone treated within the United States.

METHODS

The National Cancer Database was retrospectively inquired for all pediatric ES cases within the most updated bone and joint public use file available in September 2022. The reported data were truncated to only include patients with reported 5-year vital (ie, survival) status. Cox proportional hazard regression was conducted on both the truncated data and the entire cohort to validate the findings. The patients were then separated into alive versus deceased cohorts, and univariate regression analysis was done followed by multivariable regression of notable variables of interest.

RESULTS

Overall, an aggregated 5-year survival rate of 74.5% was found in the included patient cohort. Patients with localized cancer had a comparatively improved 5-year survival rate of 84.70% as opposed to those with macrometastatic disease on presentation with a survival rate of 50.4%. Patient demographic-, tumor-, and treatment-specific variables all demonstrated an effect on survival. The multivariable predictors of worse mortality were found to include older age, larger tumor size (>8 cm), macrometastatic disease on presentation, and positive surgical margins.

CONCLUSION

This analysis serves to establish updated survival rates of pediatric ES treated within the United States to set standards for comparison among future studies. Continued multi-institutional and international collaboration is needed to optimize current treatment results and develop novel targeted therapies.

Pediatric cancer-pathology and microenvironment influence: a perspective into osteosarcoma and non-osteogenic mesenchymal malignant neoplasms

Pediatric cancer remains the leading cause of disease-related death among children aged 1-14 years. A few risk factors have been conclusively identified, including exposure to pesticides, high-dose radiation, and specific genetic syndromes, but the etiology underlying most events remains unknown. The tumor microenvironment (TME) includes stromal cells, vasculature, fibroblasts, adipocytes, and different subsets of immunological cells. TME plays a crucial role in carcinogenesis, cancer formation, progression, dissemination, and resistance to therapy. Moreover, autophagy seems to be a vital regulator of the TME and controls tumor immunity. Autophagy is an evolutionarily conserved intracellular process. It enables the degradation and recycling of long-lived large molecules or damaged organelles using the lysosomal-mediated pathway. The multifaceted role of autophagy in the complicated neoplastic TME may depend on a specific context. Autophagy may function as a tumor-suppressive mechanism during early tumorigenesis by eliminating unhealthy intracellular components and proteins, regulating antigen presentation to and by immune cells, and supporting anti-cancer immune response. On the other hand, dysregulation of autophagy may contribute to tumor progression by promoting genome damage and instability. This perspective provides an assortment of regulatory substances that influence the features of the TME and the metastasis process. Mesenchymal cells in bone and soft-tissue sarcomas and their signaling pathways play a more critical role than epithelial cells in childhood and youth. The investigation of the TME in pediatric malignancies remains uncharted primarily, and this unique collection may help to include novel advances in this setting.

The Use of Proton and Carbon Ion Radiation Therapy for Sarcomas

The unique physical and biological characteristics of proton and carbon ions allow for improved sparing of normal tissues, decreased integral dose to the body, and increased biological effect through high linear energy transfer. These properties are particularly useful for sarcomas given their histology, wide array of locations, and age of diagnosis. This review summarizes the literature and describes the clinical situations in which these heavy particles have advantages for treating sarcomas.

Factors Influencing the Outcome of Patients with Primary Ewing Sarcoma of the Sacrum

Background

Ewing sarcoma (EwS) is a rare and highly malignant bone tumor primarily affecting children, adolescents, and young adults. The pelvis, trunk, and lower extremities are the most common sites, while EwS of the sacrum as a primary site is very rare, and only few studies focusing on this location are published. Due to the anatomical condition, local treatment is challenging in sacral malignancies. We analyzed factors that might influence the outcome of patients suffering from sacral EwS.

Methods

We retrospectively analyzed data of the GPOH EURO-E.W.I.N.G 99 trial and the EWING 2008 trial, with a cohort of 124 patients with localized or metastatic sacral EwS. The study endpoints were overall survival (OS) and event-free survival (EFS). OS and EFS were calculated using the Kaplan-Meier method, and univariate comparisons were estimated using the log-rank test. Hazard ratios (HRs) with respective 95% confidence intervals (CIs) were estimated in a multivariable Cox regression model.

Results

The presence of metastases (3y-EFS: 0.33 vs. 0.68; P < 0.001; HR = 3.4, 95% CI 1.7 to 6.6; 3y-OS: 0.48 vs. 0.85; P < 0.001; HR = 4.23, 95% CI 1.8 to 9.7), large tumor volume (≥200 ml) (3y-EFS: 0.36 vs. 0.69; P=0.02; HR = 2.1, 95% CI 1.1 to 4.0; 3y-OS: 0.42 vs. 0.73; P=0.04; HR = 2.1, 95% CI 1.03 to 4.5), and age ≥18 years (3y-EFS: 0.41 vs. 0.60; P=0.02; HR = 2.6, 95% CI 1.3 to 5.2; 3y-OS: 0.294 vs. 0.59; P=0.01; HR = 2.92, 95% CI 1.29 to 6.6) were revealed as adverse prognostic factors.

Conclusion

Young age seems to positively influence patients` survival, especially in patients with primary metastatic disease. In this context, our results support other studies, stating that older age has a negative impact on survival. Tumor volume, metastases, and the type of local therapy modality have an impact on the outcome of sacral EwS. Level of evidence: Level 2. This trial is registered with NCT00020566 and NCT00987636.

Overall survival comparison between pediatric and adult Ewing sarcoma of bone and adult nomogram construction: a large population-based analysis

Background

Ewing sarcoma (ES) is a common primary bone tumor in children. Our study aimed to compare overall survival (OS) between pediatric and adult bone ES patients, identify independent prognostic factors and develop a nomogram for predicting OS in adult patients with ES of bone.

Methods

We retrospectively analyzed data for the 2004-2015 period from the Surveillance, Epidemiology, and End Results (SEER) database. To guarantee well-balanced characteristics between the comparison groups, propensity score matching (PSM) was used. Kaplan-Meier (KM) curves were used to compare OS between pediatric and adult patients with ES of bone. Univariate and multivariate Cox regression analyses were used to screen independent prognostic factors for ES of bone, and a prognostic nomogram was constructed by using the factors identified. The prediction accuracy and clinical benefit were evaluated using receiver operating characteristic (ROC) curves, areas under the curves (AUCs), calibration curves, and decision curve analysis (DCA).

Results

Our results showed that adult ES patients had lower OS than younger ES patients. Age, surgery, chemotherapy, and TNM stage were independent risk factors for bone ES in adults and were used to develop a nomogram. AUCs for 3-, 5-, and 10-year OS were 76.4 (67.5, 85.3), 77.3 (68.6, 85.9) and 76.6 (68.6, 84.5), respectively. Calibration curves and DCA results indicated excellent performance for our nomogram.

Conclusion

We found that ES pediatric patients have better OS than adult ES patients, and we constructed a practical nomogram to predict the 3-, 5- and 10-year OS of adult patients with ES of bone based on independent prognostic factors (age, surgery, chemotherapy, T stage, N stage and M stage).

Outcomes of Pediatric Patients With Metastatic Ewing Sarcoma Treated With Interval Compression

BACKGROUND

Interval compression (IC), a regimen of alternating vincristine/doxorubicin/cyclophosphamide and ifosfamide/etoposide every 2 weeks, improves survival for localized Ewing sarcoma (ES), with uncertain effect on metastatic disease.

MATERIALS AND METHODS

We reviewed the charts of pediatric patients with metastatic ES treated with IC at our center between January 2013 and March 2020. We calculated event-free survival and overall survival (OS) and used log-rank tests for univariate comparisons.

RESULTS

We identified 34 patients 2.7 to 17.1 years of age (median: 11.6 y). Twenty-six patients (76%) had pulmonary metastases, and 14 (41%) had extrapulmonary metastases. All patients received local control therapy: surgery only (n=7, 21%), radiotherapy only (n=18, 53%), or both (n=9, 26%). The estimated 3-year OS and event-free survival were 62%±9% and 39%±9%, respectively. Patients with pulmonary-only and extrapulmonary metastasis had a 3-year OS of 88%±8% and 27%±13%, respectively ( P =0.0074). Age group (above vs. below 12 y), or primary tumor site did not affect survival, but local control therapy did (surgery only, 83%±15%; combined surgery and radiation, 30%±18%; radiation only, 15%±10%; P =0.048).

CONCLUSION

IC yielded similar outcomes for patients with metastatic ES to other reported regimens. We suggest including this approach to other blocks of therapy.

Analysis of Local Control Outcomes and Clinical Prognostic Factors in Localized Pelvic Ewing Sarcoma Patients Treated With Radiation Therapy: A Report From the Children's Oncology Group

PURPOSE

To identify potential clinical prognostic factors associated with a higher risk of local recurrence in patients with localized pelvic Ewing sarcoma treated with radiation therapy.

METHODS AND MATERIALS

Data for 101 patients treated with definitive radiation therapy (RT) or both surgery and radiation (S + RT) to primary pelvic tumors on INT-0091, INT-0154, and AEWS0031 were analyzed. Imaging data for patients who did not receive radiation were not available for central review; therefore, patients with surgery alone were not included. Cumulative incidence rates for local failure at 5 years from time of local control were calculated accounting for competing risks.

RESULTS

The most common pelvic subsite was sacrum (44.6%). RT was used in 68% of patients and S + RT in 32%. The local failure rate was 25.0% for RT and 6.3% for S + RT (P = .046). There was no statistically significant difference in local control modality by tumor characteristics. Tumors originating in the ischiopubic-acetabulum region were associated with the highest local failure incidence, 37.5% (P = .02, vs sacrum and iliac/buttock tumors), particularly those treated with RT (50.0%, P = .06). A higher incidence of local failure was seen with each additional 100 mL of tumor at diagnosis (P = .04). Multivariable analysis demonstrated RT alone (hazard ratio [HR], 5.1; P = .04), tumor subsite (particularly ischiopubic-acetabulum tumors; HR 4.6; P = .02), and increasing volume per 100 mL (HR, 1.2; P = .01) were associated with a higher incidence of local recurrence.

CONCLUSIONS

Combination surgery and RT is associated with improved local control in patients with pelvic Ewing sarcoma compared with definitive RT. Tumors involving the ischiopubic-acetabulum region and increasing tumor volume at diagnosis are associated with inferior local control. Tumor characteristics did not correlate with choice of local therapy modality suggesting an opportunity to develop best local therapy practices guidelines for future studies based on tumor features.

Multimodality treatment of pediatric Ewing sarcoma: A single-center 10-year analysis of outcomes

BACKGROUND

Ewing sarcoma, a malignancy originating from the bone or soft tissues most commonly diagnosed in adolescents, requires multimodality therapy. Although both surgical resection and radiation therapy are effective local control modalities, there are limited data comparing outcomes in patients treated with surgery versus radiation. We sought to determine whether there were differences in 5-year local failure-free survival, event-free survival, and overall survival based on the modality used for local control.

METHODS

Patients treated for Ewing sarcoma at a single tertiary pediatric hospital between 2010 and 2020 were included for retrospective analysis. Patient and tumor demographics, treatment information, and patient response to therapies were collected from the medical record. Outcome measures were local failure-free survival, event-free survival, and overall survival at 5 years from diagnosis.

RESULTS

Sixty-one patients met inclusion criteria. All patients received chemotherapy, and 68.9% of patients presented with localized disease. Of these, 23.8% were treated with radiation alone; the remaining 76.2% underwent resection ± radiation. A total of 52.4% of patients with localized disease achieved R0 resection. Only 3 patients experienced local progression; there was no difference between treatment groups. There was no significant association between local control modality and event-free survival or overall survival in patients with localized disease, regardless of margin status.

CONCLUSION

There was no significant difference in 5-year local failure-free survival, event-free survival, or overall survival in Ewing sarcoma patients treated with radiation versus surgery ± radiation, regardless of whether or not R0 resection was achieved. Future directions include a multi-institutional study to allow for further subgroup analysis and increased sample size.

Intradural Extramedullary Ewing Sarcoma in an Adolescent Female

A 15-year-old female experiencing lumbar pain without prior trauma. Despite being prescribed strong analgesics by her family physician, the symptoms intensified, and she was referred to diagnostic imaging. Magnetic resonance imaging revealed an intradural extramedullary tumor in the spinal canal, located behind the L3 corpora. The patient underwent neurosurgery with a complete resection of the tumor. The histopathologic examination revealed Ewing sarcoma by identifying EWSR1 gene in the extracted tissue. The patient was subsequently referred for extensive specialized oncological treatment including photon irradiation therapy and chemotherapy. Thirty-six months on from the initial diagnosis, the patient is doing well and suffers no sequelae apart from hypogonadism.

Extraskeletal Ewing sarcoma in children, adolescents, and young adults. An analysis of three prospective studies of the Cooperative Weichteilsarkomstudiengruppe (CWS)

BACKGROUND

We have analyzed the outcome of patients with localized extraskeletal Ewing sarcoma (EES) treated in three consecutive Cooperative Weichteilsarkomstudiengruppe (CWS) soft tissue sarcoma (STS) studies: CWS-91, CWS-96, and CWS-2002P.

METHODS

Patients were treated in CWS-91 with four- (vincristine, dactinomycin, doxorubicin, and ifosfamide [VAIA] or cyclophosphamide [VACA II]) or five-drug (+etoposide [EVAIA]) cycles, in CWS-96 they were randomly assigned to receive VAIA or CEVAIE (+carboplatin and etoposide), and in CWS-2002P with VAIA III plus optional maintenance therapy (MT) with cyclophosphamide and vinblastine. Local therapy consisted of resection and/or radiotherapy (RT).

RESULTS

Two hundred forty-three patients fulfilled the eligibility criteria. The 5-year event-free survival (EFS) and overall survival (OS) were 63% (95% confidence interval [CI] 57-69) and 73% (95% CI 67-79), respectively. The 5-year EFS by study was 64% (95% CI 54-74) in CWS-91, 57% (95% CI 48-66) in CWS-96, and 79% (95% CI 67-91) in CWS-2002P (n.s.). The 5-year OS was 72% (95% CI 62-82) in CWS-91, 70% (95% CI 61-79) in CWS-96, and 86% (95% CI 76-96) in CWS-2002P (n.s.). In CWS-96, 5-year EFS and OS in the VAIA arm versus the CEVAIE were 65% (95% CI 52-81) versus 55% (95% CI 39-76) log-rank p = .13, and 85% (95% CI 75-96) versus 61% (95% CI 45-82), log-rank p = .09.

CONCLUSION

Our analysis provides interesting information on the treatment and specificities of EES, which can be useful for a better understanding of this rare entity and should be considered in the development of future clinical trials for Ewing sarcoma defined as FET-ETS fusion positive tumors.

Pelvic Ewing sarcoma: Should all patients receive pre-operative radiotherapy, or should it be delivered selectively?

BACKGROUND

Locally recurrent disease following surgical resection of Ewing sarcoma (ES) confers a poor prognosis. Limited evidence is available evaluating non-selective use of pre-operative radiotherapy (RT) for patients with pelvic ES and its effect on local control and survival.

PATIENTS AND METHODS

49 consecutive patients with pelvic ES were identified retrospectively from a prospectively collated database. Patients either received non-selective pre-operative RT and surgery (n = 27), or selective post-operative RT (n = 22) (surgery alone (n = 11) or surgery and post-operative RT (n = 11)).

RESULTS

Patients who had non-selective pre-operative radiotherapy appeared to have a higher LRFS, 88.0% compared to 66.5% in the selective RT group (p = 0.096, Kaplan Meier; p = 0.028, Chi-squared). Administration of non-selective, pre-operative RT to all patients with pelvic ES elevates the LFRS to that of the good responder group (≥90% tumour necrosis and margins, p = 0.880). There was no difference in metastasis-free survival, 60.0% and 54.5% (p = 0.728) and overall survival (OS), 57.7% and 63.6% (p = 0.893). The majority of pre-operative RT patients had both good necrosis (≥90%) (p = 0.003) and widely excised tumours, 81.5% vs 59.1% (p = 0.080). Tumour volume ≥250 ml was associated with worse LRFS (p = 0.045) and post-operative complications (p = 0.017). There may be improved LRFS (p = 0.057) with pre-operative proton-beam RT compared to surgery and selective post-operative RT.

CONCLUSION

Pre-operative photon or proton-beam RT to all pelvic ES may improve LRFS compared to the selective delivery of post-operative RT. Radiotherapy delivered to all patients results in a greater percentage of highly necrotic tumours at surgical excision, enabling a greater proportion of patients with wide resection margins.

Ewing sarcoma

Ewing sarcoma is a rare tumor that requires complex multidisciplinary management. This report describes the general management and standard radiotherapy guidelines in both North America (Children's Oncology Group) and Europe (International Society of Pediatric Oncology). Standard treatment involves multiagent induction chemotherapy followed by local treatment with surgery, definitive radiation, or a combination of surgery and radiation followed by additional chemotherapy and consolidation local treatment to metastatic sites. The data supporting the role of chemotherapy, surgery, and radiation and specific radiation therapy guidelines are presented.

Mithramycin A Radiosensitizes EWS:Fli1+ Ewing Sarcoma Cells by Inhibiting Double Strand Break Repair

PURPOSE

The oncogenic EWS:Fli1 fusion protein is a key transcriptional mediator of Ewing sarcoma initiation, progression, and therapeutic resistance. Mithramycin A (MithA) is a potent and specific inhibitor of transcription mediated by the EWS:Fli1. We tested the hypothesis that pretreatment with MithA could selectively radiosensitize EWS:Fli1⁺ tumor cells by altering the transcriptional response to radiation injury.

METHODS AND MATERIALS

A panel of 4 EWS:Fli1⁺ and 3 EWS:Fli1^- Ewing sarcoma cell lines and 1 nontumor cell line were subjected to MithA dose-response viability assays to determine the relative potency of MithA in cells possessing or lacking the EWS:Fli1 fusion. Radiosensitization by MithA was evaluated by clonogenic survival assays in vitro and in a murine xenograft model. DNA damage was evaluated by comet assay and γ-H2Ax flow cytometry. Immunoblotting, flow cytometry, and reverse-transcription, polymerase chain reaction were used to evaluate DNA damage-induced signaling and repair processes and apoptosis.

RESULTS

We found that MithA alone could potently and selectively inhibit the growth of EWS:Fli1⁺ tumor cells, but not cells lacking this fusion. Pretreatment with MithA for 24 hours before irradiation significantly reduced clonogenic survival in vitro and delayed tumor regrowth in vivo, prolonging survival of EWS:Fli1⁺ tumor-bearing mice. Although MithA did not increase the level of DNA double-strand breaks, mechanistic studies revealed that MithA pretreatment selectively inhibited DNA double-strand break repair through downregulation of EWS:Fli1-mediated transcription, leading to tumor cell death by apoptosis.

CONCLUSIONS

Our data indicate that MithA is an effective radiosensitizer of EWS:Fli1⁺ tumors and may achieve better local control at lower doses of radiation.

Establishing a novel prognostic tool for Ewing sarcoma patients: Surveillance, Epidemiology, and End Results database analysis

Patients diagnosed with Ewing sarcoma (ES) usually experience poor outcomes. Accurate prediction of ES patients' prognosis is essential to improve their survival. Given that ES is a relatively rare tumor with a low incidence, we aim at developing a prognostic nomogram of ES patients based on a large sample analysis.We used the Surveillance, Epidemiology, and End Results (SEER) database to screen eligible patients diagnosed ES of bone. This retrospective study presented the clinicopathological characteristics and prognosis of ES. We randomly assigned all ES patients to 2 sets (training set and validation set) with an equal number of patients. In order to identify independent factors of survival, we performed univariate and multivariate Cox analysis in the training set. Then, we constructed novel nomograms to predict survival of ES patients by integrating significant independent variables from the training set. The prognostic performance of constructed nomograms was examined using concordance index (C-index) and calibration curves in both training and validation set.We included a total of 988 eligible cases diagnosed ES of bone between 2000 and 2015. Age >18 years, distant metastasis, tumor size >10 cm, and no surgery were independent risk factors for poorer survival. Our survival prediction nomograms were established based on those 4 independent risk factors. Good calibration plots were achieved in internal and external validation. The internal validation C-indexes of the nomogram for overall survival (OS) and cancer-specific survival (CSS) were 0.733 and 0.737, respectively. Similar good results were also achieved in external validation setting.The established nomograms show good performance and allow for better evaluating the prognosis of ES patients and recommending appropriate instructions.

Current Status and Perspectives of Patient-Derived Models for Ewing's Sarcoma

Simple Summary

A paucity of patient-derived cancer models hinders the development of novel therapeutic strategies in Ewing’s sarcoma. This review aimed to demonstrate the utility and possibility of popular patient-derived cancer models by overviewing the reported studies and to encourage the researchers to develop more models for Ewing’s sarcoma.

Abstract

Patient-derived cancer models, including cell lines, organoids, and xenografts, are indispensable tools in cancer research. These models, which recapitulate molecular features of original tumors, allow studies on the biological significance of cancer-associated genes, antitumor effects of novel agents, and molecular mechanisms underlying clinical behaviors of tumors. Moreover, the predictive utility of patient-derived cancer models is expected to facilitate drug development and precision medicine. Ewing’s sarcoma is a highly aggressive mesenchymal tumor with a high metastasis rate. Previous studies demonstrated the utility of cell lines and xenografts in Ewing’s sarcoma research and clinical studies. However, the number of Ewing’s sarcoma models available from public biobanks is limited; this creates an obstacle for research on Ewing’s sarcoma. Novel Ewing’s sarcoma models are needed to establish their utility, further our understanding of the molecular mechanisms, and help develop effective therapeutic strategies. In this review, the current status of patient-derived cancer models is overviewed, and future prospects of model development are discussed from the perspective of Ewing’s sarcoma research. It should be of interest to researchers and clinicians who work on patient-derived cancer models.

Proximal femur sarcomas with intra-articular disease-Do intra-articular resections provide adequate local control?

BACKGROUND AND OBJECTIVES

Hip preserving (intra-articular) resections for proximal femur sarcoma have better function compared to peri-acetabular (extra-articular) resections, which are more complex and morbid. But, do intra-articular resections in selected cases with intra-articular disease provide adequate local control?

METHOD

Extra-articular resection or intra-articular resection in cases without pathologic fracture or away from joint/capsule was classified as a planned safe margin (SM). Circumferential removal of labrum without acetabular resection in cases without gross joint contamination was classified as planned close margins (CM). We analyzed local recurrence-free survival (LRFS) (death as a competing event) for 86 proximal femur resections (SM = 55, CM = 31).

RESULTS

The 5 years LRFS was 84% (n = 6/55, 10%) in the SM group and 67% (n = 4/31, 12%) in the CM group. There was no worsening of local recurrence (LR) in the CM group (subdistribution hazard [sH] = 0.69; 95% confidence interval [CI], 0.21-2.29; P = .56). Poor chemotherapy-induced necrosis predicted worse LR (sH = 0.1; 95% CI, 0.01-0.8; P = .03). Overall survival was 16% (SE 8%) at 5 years with LR vs 64% (SE 7%) without LR (P = .0076).

CONCLUSION

In proximal femur sarcomas with potential for involvement of the hip joint, a CM in selected cases did not worsen LR; providing an option for avoiding additional morbidity with extra-articular resections.

Clinical research methods for treatment, diagnosis, prognosis, etiology, screening, and prevention: A narrative review

This narrative review is an introduction for health professionals on how to conduct and report clinical research on six categories: treatment, diagnosis/differential diagnosis, prognosis, etiology, screening, and prevention. The importance of beginning with an appropriate clinical question and the exploration of how appropriate it is through a literature search are explained. There are three methodological directives that can assist clinicians in conducting their studies from a methodological perspective: (1) how to conduct an original study or a systematic review, (2) how to report an original study or a systematic review, and (3) how to assess the quality or risk of bias for a previous relevant original study or systematic review. This methodological overview article would provide readers with the key points and resources regarding how to perform high-quality research on the six main clinical categories.

Which Factors Are Associated with Local Control and Survival of Patients with Localized Pelvic Ewing's Sarcoma? A Retrospective Analysis of Data from the Euro-EWING99 Trial

BACKGROUND

Local treatment of pelvic Ewing's sarcoma may be challenging, and intergroup studies have focused on improving systemic treatments rather than prospectively evaluating aspects of local tumor control. The Euro-EWING99 trial provided a substantial number of patients with localized pelvic tumors treated with the same chemotherapy protocol. Because local control included surgical resection, radiation therapy, or a combination of both, we wanted to investigate local control and survival with respect to the local modality in this study cohort.

QUESTIONS/PURPOSES

(1) Do patients with localized sacral tumors have a lower risk of local recurrence and higher survival compared with patients with localized tumors of the innominate bones? (2) Is the local treatment modality associated with local control and survival in patients with sacral and nonsacral tumors? (3) Which local tumor- and treatment-related factors, such as response to neoadjuvant chemotherapy, institution where the biopsy was performed, and surgical complications, are associated with local recurrence and patient survival in nonsacral tumors? (4) Which factors, such as persistent extraosseous tumor growth after chemotherapy or extent of bony resection, are independently associated with overall survival in patients with bone tumors undergoing surgical treatment?

METHODS

Between 1998 and 2009, 1411 patients with previously untreated, histologically confirmed Ewing's sarcoma were registered in the German Society for Pediatric Oncology and Hematology Ewing's sarcoma database and treated in the Euro-EWING99 trial. In all, 24% (339 of 1411) of these patients presented with a pelvic primary sarcoma, 47% (159 of 339) of which had macroscopic metastases at diagnosis and were excluded from this analysis. The data from the remaining 180 patients were reviewed retrospectively, based on follow-up data as of July 2016. The median (range) follow-up was 54 months (5 to 191) for all patients and 84 months (11 to 191) for surviving patients. The study endpoints were overall survival, local recurrence and event-free survival probability, which were calculated with the Kaplan-Meier method and compared using the log-rank test. Hazard ratios (HRs) with their respective 95% CIs were estimated in a multivariate Cox regression model.

RESULTS

Sacral tumors were associated with a reduced probability of local recurrence (12% [95% CI 1 to 22] versus 28% [95% CI 20 to 36] at 5 years, p = 0.032), a higher event-free survival probability (66% [95% CI 51 to 81] versus 50% [95% CI 41 to 58] at 5 years, p = 0.026) and a higher overall survival probability (72% [95% CI 57 to 87] versus 56% [95% CI 47 to 64] at 5 years, p = 0.025) compared with nonsacral tumors. With the numbers available, we found no differences between patients with sacral tumors who underwent definitive radiotherapy and those who underwent combined surgery and radiotherapy in terms of local recurrence (17% [95% CI 0 to 34] versus 0% [95% CI 0 to 20] at 5 years, p = 0.125) and overall survival probability (73% [95% CI 52 to 94] versus 78% [95% CI 56 to 99] at 5 years, p = 0.764). In nonsacral tumors, combined local treatment was associated with a lower local recurrence probability (14% [95% CI 5 to 23] versus 33% [95% CI 19 to 47] at 5 years, p = 0.015) and a higher overall survival probability (72% [95% CI 61 to 83] versus 47% [95% CI 33 to 62] at 5 years, p = 0.024) compared with surgery alone. Even in a subgroup of patients with wide surgical margins and a good histologic response to induction treatment, the combined local treatment was associated with a higher overall survival probability (87% [95% CI 74 to 100] versus 51% [95% CI 33 to 69] at 5 years, p = 0.009), compared with surgery alone.A poor histologic response to induction chemotherapy in nonsacral tumors (39% [95% CI 19 to 59] versus 64% [95% CI 52 to 76] at 5 years, p = 0.014) and the development of surgical complications after tumor resection (35% [95% CI 11 to 59] versus 68% [95% CI 58 to 78] at 5 years, p = 0.004) were associated with a lower overall survival probability in nonsacral tumors, while a tumor biopsy performed at the same institution where the tumor resection was performed was associated with lower local recurrence probability (14% [95% CI 4 to 24] versus 32% [95% CI 16 to 48] at 5 years, p = 0.035), respectively.In patients with bone tumors who underwent surgical treatment, we found that after controlling for tumor localization in the pelvis, tumor volume, and surgical margin status, patients who did not undergo complete (defined as a Type I/II resection for iliac bone tumors, a Type II/III resection for pubic bone and ischium tumors and a Type I/II/III resection for tumors involving the acetabulum, according to the Enneking classification) removal of the affected bone (HR 5.04 [95% CI 2.07 to 12.24]; p < 0.001), patients with a poor histologic response to induction chemotherapy (HR 3.72 [95% CI 1.51 to 9.21]; p = 0.004), and patients who did not receive additional radiotherapy (HR 4.34 [95% CI 1.71 to 11.05]; p = 0.002) had a higher risk of death. The analysis suggested that the same might be the case in patients with a persistent extraosseous tumor extension after induction chemotherapy (HR 4.61 [95% CI 1.03 to 20.67]; p = 0.046), although the wide CIs pointing at a possible sparse-data bias precluded any definitive conclusions.

CONCLUSION

Patients with sacral Ewing's sarcoma appear to have a lower probability for local recurrence and a higher overall survival probability compared with patients with tumors of the innominate bones. Our results seem to support a recent recommendation of the Scandinavian Sarcoma Group to locally treat most sacral Ewing's sarcomas with definitive radiotherapy. Combined surgical resection and radiotherapy appear to be associated with a higher overall survival probability in nonsacral tumors compared with surgery alone, even in patients with a wide resection and a good histologic response to neoadjuvant chemotherapy. Complete removal of the involved bone, as defined above, in patients with nonsacral tumors may be associated with a decreased likelihood of local recurrence and improved overall survival. Persistent extraosseous tumor growth after induction treatment in patients with nonsacral bone tumors undergoing surgical treatment might be an important indicator of poorer overall survival probability, but the possibility of sparse-data bias in our cohort means that this factor should first be validated in future studies.

LEVEL OF EVIDENCE

Level III, therapeutic study.

What is the Likelihood That Tumor Endoprostheses Will Experience a Second Complication After First Revision in Patients With Primary Malignant Bone Tumors And What Are Potential Risk Factors?

BACKGROUND

Endoprosthetic reconstruction of massive bone defects has become the reconstruction method of choice after limb-sparing resection of primary malignant tumors of the long bones. Given the improved survival rates of patients with extremity bone sarcomas, an increasing number of patients survive but have prosthetic complications over time. Several studies have reported on the outcome of first endoprosthetic complications. However, no comprehensive data, to our knowledge, are available on the likelihood of an additional complication and the associated risk factors, despite the impact of this issue on the affected patients.

QUESTIONS/PURPOSES

(1) What are the types and timing of complications and the implant survivorship free from revision after the first complication? (2) Does survivorship free from repeat revision for a second complication differ by anatomic sites? (3) Is the type of first complication associated with the risk or the type of a second complication? (4) Are patient-, tumor-, and treatment-related factors associated with a higher likelihood of repeat revision?

METHODS

Between 1993 and 2015, 817 patients underwent megaprosthetic reconstruction after resection of a tumor in the long bones with a single design of a megaprosthetic system. No other prosthetic system was used during the study period. Of those, 75% (616 of 817) had a bone sarcoma. Seventeen patients (3%) had a follow-up of less than 6 months, 4.5% (27 of 599) died with the implant intact before 6 months and 43% (260 of 599 patients) underwent revision. Forty-three percent of patients (260 of 599) experienced a first prosthetic complication during the follow-up period. Ten percent of patients (26 of 260) underwent amputation after the first complication and were excluded from further analysis. Second complications were classified using the classification of Henderson et al. to categorize surgical results. Briefly, this system categorizes complications as wound dehiscence (Type 1); aseptic loosening (Type 2); implant fractures or breakage and periprosthetic fracture (Type 3); infection (Type 4); and tumor progression (Type 5). Implant survival curves were calculated with the Kaplan-Meier method and compared using the log-rank test. Hazard ratios (HR) were estimated with their respective 95% CIs in multivariate Cox regression models.

RESULTS

A second complication occurred in 49% of patients (115 of 234) after a median of 17 months (interquartile range [IQR] 5 to 48) after the surgery for the first complication. The time to complication did not differ between the first (median 16 months; IQR 5 to 57) and second complication (median 17 months; IQR 5 to 48; p = 0.976). The implant survivorship free from revision surgery for a second complication was 69% (95% CI 63 to 76) at 2 years and 46% (95% CI 38 to 53) at 5 years. The most common mode of second complication was infection 39% (45 of 115), followed by structural complications with 35% (40 of 115). Total bone and total knee reconstructions had a reduced survivorship free from revision surgery for a second complication at 5 years (HR 2.072 [95% CI 1.066 to 3.856]; p = 0.031) compared with single joint replacements. With the numbers we had, we could not show a difference between the survivorship free of revision for a second complication based on the type of the first complication (HR 0.74 [95% CI 0.215 to 2.546]; p = 0.535). We did not detect an association between total reconstruction length, patient BMI, and patient age and survivorship free from revision for a second complication. Patients had a higher risk of second complications after postoperative radiotherapy (HR 1.849 [95% CI 1.092 to 3.132]; p = 0.022) but not after preoperative radiotherapy (HR 1.174 [95% CI 0.505 to 2.728]; p = 0.709). Patients with diabetes at the time of initial surgery had a reduced survivorship free from revision for a second complication (HR 4.868 [95% CI 1.497 to 15.823]; p = 0.009).

CONCLUSIONS

Patients who undergo revision to treat a first megaprosthetic complication must be counseled regarding the high risk of future complications. With second complications occurring relatively soon after the first revision, regular orthopaedic follow-up visits are advised. Preoperative rather than postoperative radiotherapy should be performed when possible. Future studies should evaluate the effectiveness of different approaches in treating complications considering implant survivorship free of revision for a second complication.

LEVEL OF EVIDENCE

Level III, therapeutic study.

The Tumor Microenvironment of Pediatric Sarcoma: Mesenchymal Mechanisms Regulating Cell Migration and Metastasis

PURPOSE OF REVIEW

This review presents a selection of regulatory molecules of tumor microenvironmental properties and metastasis. Signaling pathways controlling mesenchymal biology in bone and soft-tissue sarcomas found in children and adolescents are prioritized.

RECENT FINDINGS

The tumor microenvironment of pediatric tumors is still relatively unexplored. Highlighted findings are mainly on deregulated genes associated with cell adhesion, migration, and tumor cell dissemination. How these processes are involved in a mesenchymal phenotype and metastasis is further discussed in relation to the epithelial to mesenchymal transition (EMT) in epithelial tumors. Cell plasticity is emerging as a concept with impact on tumor behavior. Sarcomas belong to a heterogeneous group of tumors where local recurrence and tumor spread pose major challenges despite intense multimodal treatments. Molecular pathways involved in the metastatic process are currently being characterized, and tumor-regulatory properties of structural components, and infiltrating, non-malignant cell types should be further investigated.

Exploiting Signaling Pathways and Immune Targets Beyond the Standard of Care for Ewing Sarcoma

Ewing sarcoma (ES) family of tumors includes bone and soft tissue tumors that are often characterized by a specific translocation between chromosome 11 and 22, resulting in the EWS-FLI1 fusion gene. With the advent of multi-modality treatment including cytotoxic chemotherapy, surgery, and radiation therapy, the prognosis for patients with ES has substantially improved. However, a therapeutic plateau is now reached for both localized and metastatic disease over the last two decades. Burdened by the toxicity limits associated with the current frontline systemic therapy, there is an urgent need for novel targeted therapeutic strategies. In this review, we discuss the current treatment paradigm of ES, and explore preclinical evidence and emerging treatments directed at tumor signaling pathways and immune targets.

Surgical Resection of Primary Ewing's Sarcoma of Bone Improves Overall Survival in Patients Presenting with Metastasis

Background

Metastatic Ewing’s sarcoma (ES) of bone has a poor prognosis. Because there have been few previous studies on the prognostic factors and clinical outcome in patients with ES who have metastases at presentation, the aim of this study was to use the Surveillance, Epidemiology, and End Results (SEER) database to compare the clinical outcome following single and combined radiation treatment and surgery.

Material/Methods

The SEER database was used to identify patients with ES who presented with bone involvement and metastasis between 1973 to 2015. Prognostic analysis was performed using the Kaplan-Meier method and the Cox proportional hazards regression model.

Results

There were 643 patients identified from the SEER database. The 5-year overall survival (OS) and cancer-specific survival (CSS) rates were 33.1% and 34.3%, respectively and the median OS and CSS were 29.0±1.9 and 29.0±2.1 months, respectively. Multivariate analysis identified age <20 years and surgical resection of the primary tumor to be significantly associated with improved OS. Radiation therapy was not an independent predictor of OS or CSS. Radiation therapy alone resulted in a significantly reduced the OS and CSS compared with surgical resection alone. Combined surgery and radiation therapy of the primary tumor did not significantly improve the OS or CSS of patients with ES and metastatic disease when compared with surgery alone.

Conclusions

Age <20 years and surgical resection of the primary tumor were significantly associated with improved OS in patients with primary ES of bone who presented with metastasis.

Introducing fluorescence guided surgery into orthopedic oncology: A systematic review of candidate protein targets for Ewing sarcoma

Ewing sarcoma (ES), an aggressive bone and soft‐tissue tumor, is treated with chemotherapy, radiotherapy, and surgery. Intra‐operative distinction between healthy and tumorous tissue is of paramount importance but challenging, especially after chemotherapy and at complex anatomical locations. Near infrared (NIR) fluorescence‐guided surgery (FGS) is able to facilitate the determination of tumor boundaries intra‐operatively, improving complete resection and therefore survival. This review evaluates potential ES‐specific proteins from the literature as targets for NIR FGS.

Survival is influenced by approaches to local treatment of Ewing sarcoma within an international randomised controlled trial: analysis of EICESS-92

Background

Two national clinical trial groups, United Kingdom Children’s Cancer and Leukaemia Group (CCLG) and the German Paediatric Oncology and Haematology Group (GPOH) together undertook a randomised trial, EICESS-92, which addressed chemotherapy options for Ewing’s sarcoma. We sought the causes of unexpected survival differences between the study groups.

Methods

647 patients were randomised. Cox regression analyses were used to compare event-free survival (EFS) and overall survival (OS) between the two study groups.

Results

5-year EFS rates were 43% (95% CI 36–50%) and 57% (95% CI 52–62) in the CCLG and GPOH patients, respectively; corresponding 5-year OS rates were 52% (95% CI 45–59%) and 66% (95% CI 61–71). CCLG patients were less likely to have both surgery and radiotherapy (18 vs. 59%), and more likely to have a single local therapy modality compared to the GPOH patients (72 vs. 35%). Forty-five percent of GPOH patients had pre-operative radiotherapy compared to 3% of CCLG patients. In the CCLG group local recurrence (either with or without metastases) was the first event in 22% of patients compared with 7% in the GPOH group. After allowing for the effects of age, metastases, primary site, histology and local treatment modality, the risk of an EFS event was 44% greater in the CCLG cohort (95% CI 10–89%, p = 0.009), and the risk of dying was 30% greater, but not statistically significant (95% CI 3–74%, p = 0.08).

Conclusions

Unexpected differences in EFS and OS occurred between two patient cohorts recruited within an international randomised trial. Failure to select or deliver appropriate local treatment modalities for Ewing’s sarcoma may compromise chances of cure.

Trial registration Supported by Deutsche Krebshilfe (Grants No. DKH M43/92/Jü2 and DKH 70-2551 Jü3), and European Union Biomedicine and Health Programme (Grants No. BMH1-CT92-1341 and BMH4-983956), and Cancer Research United Kingdom. Clinical trial information can be found for the following: NCT0000251

Comparison of the effects of local treatment strategies in non-metastatic Ewing sarcoma of bone

BACKGROUND

To investigate the optimal local treatment strategies for patients with non-metastatic Ewing sarcoma (ES) of bone.

METHODS

Patients with ES of bone were identified using the Surveillance Epidemiology and End Results database. Kaplan-Meier log-rank test and Cox regression models were performed to assess the effect of the types of local treatment strategies on cause-specific survival and overall survival.

RESULTS

560 patients were included with a median age of 16 years. A total of 284, 162 and 114 patients received surgery alone, surgery and radiotherapy, and radiotherapy alone, respectively. The types of local treatment strategies had no effect on survival outcomes in multivariate analysis. In the subgroup analysis of patients with tumor diameter <8 cm, surgery ± radiotherapy had a significantly improved cause-specific survival (P = 0.039), and had potential to improve overall survival (P = 0.070) in multivariate analysis. The local treatment strategies had no effect on survival in patients with different tumor location.

CONCLUSION

There is no local treatment of choice for non-metastatic ES of bone in terms of survival. More well-designed studies are needed to confirm our findings and investigate the role of various local treatment strategies in relation to primary tumor diameter.

Planning for Bone Excision in Ewing Sarcoma: Post-Chemotherapy MRI More Accurate Than Pre-Chemotherapy MRI Assessment

BACKGROUND

In determining the level of bone resection in Ewing sarcoma, the most suitable time at which to perform magnetic resonance imaging (MRI) remains controversial. Current guidelines recommend that surgical planning be based on MRI performed prior to neoadjuvant chemotherapy. The goal of this study was to determine whether pre-chemotherapy or post-chemotherapy MRI provides greater accuracy of tumor limits for planning bone excision in the management of Ewing sarcoma.

METHODS

This was a single-center, retrospective study. MRI was performed using 3 sequences: T1-weighted, T1-weighted with contrast enhancement by gadolinium injection, and a fluid-sensitive sequence (STIR [short tau inversion recovery] or proton-density-weighted with fat saturation). The tumor extent as assessed on pre-chemotherapy and post-chemotherapy MRI was compared with histological measurement of the resected specimen.

RESULTS

Twenty patients with Ewing sarcoma of a long bone were included. In 6 cases, the tumor was located on the femur, in 5, the tibia; in 5, the fibula; and in 4, the humerus. The median patient age at diagnosis was 9.7 years. We found greater accuracy of measurements from MRI scans acquired after chemotherapy than from those acquired before chemotherapy. For both pre-chemotherapy and post-chemotherapy MRI, the greatest accuracy was achieved with the nonenhanced T1 sequence. There was no benefit to gadolinium enhancement. The median difference between T1 MRI and histological measurements was 19.0 mm (interquartile range [IQR], 4.3 to 32.8 mm) before chemotherapy and 5.0 mm (IQR, 2.0 to 13.0 mm) after chemotherapy. Adding a minimum margin of 20 mm to the limit of the tumor on post-chemotherapy T1 MRI always led to safe histological margin.

CONCLUSIONS

Post-chemotherapy MRI provided a more accurate assessment of the limits of Ewing sarcoma. Surgical planning can therefore be based on post-chemotherapy MRI. Surgical cuts can be, at minimum, 20 mm from the limits as seen on MRI.

DNA Methylation-Based Classifier for Accurate Molecular Diagnosis of Bone Sarcomas

Purpose

Pediatric sarcomas provide a unique diagnostic challenge. There is considerable morphologic overlap between entities, increasing the importance of molecular studies in the diagnosis, treatment, and identification of therapeutic targets. We developed and validated a genome-wide DNA methylation based classifier to differentiate between osteosarcoma, Ewing's sarcoma, and synovial sarcoma.

Materials and Methods

DNA methylation status of 482,421 CpG sites in 10 Ewing's sarcoma, 11 synovial sarcoma, and 15 osteosarcoma samples were determined using the Illumina Infinium HumanMethylation450 array. We developed a random forest classifier trained from the 400 most differentially methylated CpG sites within the training set of 36 sarcoma samples. This classifier was validated on data drawn from The Cancer Genome Atlas (TCGA) synovial sarcoma, TARGET Osteosarcoma, and a recently published series of Ewing's sarcoma.

Results

Methylation profiling revealed three distinct patterns, each enriched with a single sarcoma subtype. Within the validation cohorts, all samples from TCGA were accurately classified as synovial sarcoma (10/10, sensitivity and specificity 100%), all but one sample from TARGET-OS were classified as osteosarcoma (85/86, sensitivity 98%, specificity 100%) and 14/15 Ewing's sarcoma samples classified correctly (sensitivity 93%, specificity 100%). The single misclassified osteosarcoma sample demonstrated high EWSR1 and ETV1 expression on RNA-seq although no fusion was found on manual curation of the transcript sequence. Two additional clinical samples, that were difficult to classify by morphology and molecular methods, were classified as osteosarcoma when previously suspected to be a synovial sarcoma and Ewing's sarcoma on initial diagnosis, respectively.

Conclusion

Osteosarcoma, synovial sarcoma, and Ewing's sarcoma have distinct epigenetic profiles. Our validated methylation-based classifier can be used to provide diagnostic assistance when histological and standard techniques are inconclusive.

Evidence-based guideline recommendations on treatment strategies for localized Ewing's sarcoma of bone following neo-adjuvant chemotherapy

OBJECTIVES

(1) To provide recommendations regarding the choice of surgery, radiation therapy (RT), or the combination of surgery plus RT in patients with localized Ewing's sarcoma of bone following neoadjuvant chemotherapy. (2) To determine the appropriate surgical planning imaging (pre-chemotherapy magnetic resonance imaging [MRI] or post-chemotherapy MRI) to identify optimal resection margins in patients with localized Ewing's sarcoma who undergo surgery following neoadjuvant chemotherapy.

METHODS

MEDLINE, EMBASE, the Cochrane Library (1999 to February 2015), main guideline websites, and relevant annual meeting abstracts (2012 to January 2015) were searched. Internal and external reviews were conducted.

RECOMMENDATIONS

1. Recommendation (1) - In patients with localized Ewing's sarcoma of bone following neoadjuvant chemotherapy: (a) Surgery alone or RT alone are two reasonable treatment options; the combination of surgery plus RT is not recommended as an initial treatment option. (b) The local treatment for an individual patient should be decided by a multidisciplinary tumour board together with the patient after consideration of the following: (1) patient characteristics (e.g., age, tumour location, tumour size, response to neoadjuvant chemotherapy, and existing comorbidities), (2) the potential benefit weighed against the potential complications from surgery and/or toxicities associated with RT, and (3) patient preferences. 2. Recommendation (2) - In patients with localized Ewing's sarcoma who will undergo surgery: (a) Both pre-chemotherapy and post-chemotherapy MRI scans should be taken into consideration for surgical planning. In certain anatomic locations with good chemotherapy response, the post-chemotherapy MRI may be the appropriate imaging modality to plan surgical resection margins.