Individual risk evaluation for local recurrence and distant metastasis in Ewing sarcoma: A multistate model: A multistate model for Ewing sarcoma.

BACKGROUND: We investigated the effects of surgical margins, histological response, and radiotherapy on local recurrence (LR), distant metastasis (DM), and survival in Ewing sarcoma. PROCEDURE: Disease evolution was retrospectively studied in 982 patients with Ewing sarcoma undergoing surgery after chemotherapy using a multistate model with initial state surgery, intermediate states LR, pulmonary metastasis (DMpulm), other DM ± LR (DMother), and final state death. Effect of risk factors was estimated using Cox proportional hazard models. RESULTS: The median follow-up was 7.6 years (95% CI, 7.2-8.0). Risk factors for LR are pelvic location, HR 2.04 (1.10-3.80), marginal/intralesional resection, HR 2.28 (1.25-4.16), and radiotherapy, HR 0.52 (0.28-0.95); for DMpulm the risk factors are <90% necrosis, HR 2.13 (1.13-4.00), and previous pulmonary metastasis, HR 4.90 (2.28-8.52); for DMother are 90% to 99% necrosis, HR 1.56 (1.09-2.23), <90% necrosis, HR 2.66 (1.87-3.79), previous bone/other metastasis, HR 3.08 (2.03-4.70); and risk factors for death without LR/DM are pulmonary metastasis, HR 8.08 (4.01-16.29), bone/other metastasis, HR 10.23 (4.90-21.36), and <90% necrosis, HR 6.35 (3.18-12.69). Early LR (0-24 months) negatively influences survival, HR 3.79 (1.34-10.76). Once DMpulm/DMother arise only previous bone/other metastasis remain prognostic for death, HR 1.74 (1.10-2.75). CONCLUSION: Disease extent and histological response are risk factors for progression to DM or death. Tumor site and surgical margins are risk factors for LR. If disease progression occurs, previous risk factors lose their relevance. In case of isolated LR, time to recurrence is important for decision-making. Radiotherapy seems protective for LR especially in pelvic/axial. Low percentages of LR in extremity tumors and associated toxicity question the need for radiotherapy in extremity Ewing sarcoma.

Easy-to-use clinical tool for survival estimation in Ewing sarcoma at diagnosis and after surgery.

Accurate survival estimations in Ewing sarcoma are necessary to develop risk- and response adaptive treatment strategies allowing for early decision-making. We aim to develop an easy-to-use survival estimation tool from diagnosis and surgery. A retrospective study of 1314 Ewing sarcoma patients was performed. Associations between prognostic variables at diagnosis/surgery and overall survival (OS), were investigated using Kaplan-Meier and multivariate Cox models. Predictive accuracy was evaluated by cross-validation and Harrell C-statistics. Median follow-up was 7.9 years (95%CI 7.6-8.3). Independent prognostic factors at diagnosis were age, volume, primary tumor localization and disease extent. 5 risk categories (A-E) were identified with 5-year OS of 88% (86-94), 69% (64-74), 57% (50-64), 51% (42-60) and 28% (22-34) respectively. Harrell C-statistic was 0.70. Independent prognostic factors from surgery were age, volume, disease extent and histological response. In categories A-B, 5y OS increased to 92% (87-97) and 79% (71-87) respectively for 100% necrosis and decreased to 76% (67-85) and 62% (55-69) respectively for <100% necrosis. In categories C-E, 5y OS increased to 65% (55-75), 65% (52-78) and 52% (38-66) respectively for ≥90% necrosis and decreased to 38% (22-54), 11% (0-26) and 7% (0-19) respectively for <90% necrosis. We present an easy-to-use survival estimation tool from diagnosis in Ewing sarcoma based on age, volume, primary tumor localization and disease extent. Histological response is a strong additional prognostic factor for OS.

18F-FDG PET-CT versus MRI for detection of skeletal metastasis in Ewing sarcoma.

OBJECTIVE: To determine the level of discrepancy between magnetic resonance imaging (MRI) and 18F-FDG PET-CT in detecting osseous metastases in patients with Ewing sarcoma. METHODS: Twenty patients with histopathologically confirmed Ewing sarcoma between 2000 and 2017 who underwent 18F-FDG PET-CT and MRI within a 4-week range were included. Each imaging modality was evaluated by a separate observer. Reference diagnosis of each lesion was based on histopathology or consensus of an expert panel using all available data, including at least 6 months' follow-up. Sensitivity, specificity, and predictive values were determined. Osseous lesions were analyzed on a patient and a lesion basis. Factors possibly related to false-negative findings were evaluated using Pearson's Chi-squared or Fisher's exact test. RESULTS: A total of 112 osseous lesions were diagnosed in 13 patients, 107 malignant and 5 benign. Seven patients showed no metastases on either 18F-FDG PET-CT or MRI. Forty-one skeletal metastases (39%) detected with MRI did not show increased 18F-FDG uptake on 18F-FDG PET-CT (false-negative). Lesion-based sensitivities and specificities were 62% (95%CI 52-71%) and 100% (48-100%) for 18F-FDG PET-CT; and 99% (97-100%) and 100% (48-100%) for MRI respectively. Bone lesions were more likely to be false-negative on 18F-FDG PET-CT if hematopoietic bone marrow extension was widespread and active (p = 0.001), during or after (neo)-adjuvant treatment (p = 0.001) or when the lesion was smaller than 10 mm (p < 0.001). CONCLUSION: Although no definite conclusions can be drawn from this small retrospective study, it shows that caution is needed when using 18F-FDG PET-CT for diagnosing skeletal metastases in Ewing sarcoma. Poor contrast between metastases and active hematopoietic bone marrow, chemotherapeutic treatment, and/or small size significantly decrease the diagnostic yield of 18F-FDG PET-CT, but not of MRI.

Prognostic factors for survival in Ewing sarcoma: A systematic review.

Development of a prognostic model for survival can assist in stratifying treatment according to the individual patients' risk, leading to risk- and response adaptive treatment strategies which allow for early decision making. The aim of this systematic review is to provide an overview of prognostic factors for overall survival (OS) and event-free survival (EFS) in Ewing sarcoma to be used in the development of prediction models and clinical trial design. A literature search was performed using Pubmed, Embase, Web of Science, Academic search premier and Cochrane databases. Studies were eligible if: 1) Sample size ≥100; 2) Follow-up ≥2 years or dead within 2 years; 3) Recruitment after 1975; 4) Outcome measure OS or EFS; 5) Multivariate analysis to assess the effect of prognostic factors on survival outcomes; 6) Study published in English. In case studies were derived from the same database the most all-embracing was selected. Study selection and quality assessment was performed by two reviewers independently. For each risk factor a level of evidence synthesis was performed. Kappa-statistic was used to determine inter-observer agreement. A total of 149 full-text articles were found, 21 eligible for inclusion. 24 prognostic factors were investigated, 14 relevant for this review. Prognostic factors associated with survival include metastasis at diagnosis, large tumors (volume ≥ 200 ml or largest diameter ≥ 8 cm), primary tumors located in the axial skeleton, especially pelvic and a histological response of less than 100%. These factors should be included as risk factors in the development of prediction models for ES.