The Utility of 18FDG PET/CT Versus Bone Scan for Identification of Bone Metastases in a Pediatric Sarcoma Population and a Review of the Literature

Role of 18F-Fluorodeoxyglucose Positron Emission Tomography in Children With Germ Cell Tumor After Chemotherapy

BACKGROUND/AIM

18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) is a diagnostic tool widely used in adult oncology and some pediatric oncological settings. There are no established recommendations for the use of this imaging modality in pediatric malignant germ cell tumors (mGCT), however. Our aim is to evaluate the role of 18F-FDG PET/CT in the restaging of mGCT after chemotherapy in children and adolescents.

METHODS

We retrospectively reviewed patients with mGCT treated in Associazione Italiana Ematologia Oncologia Pediatrica (AIEOP) centers who underwent 18F-FDG PET/CT between 2011 and 2021.

RESULTS

Seventeen patients (median age 13 y) were included in the study. In 14 patients, 18F-FDG PET/CT was performed at diagnosis; 12 showed pathologic uptake. The 2 18F-FDG PET/CT negative cases were histologically defined as yolk sac tumor (YST) and mixed (chorioncarcinoma, YST). Nine of the 12 patients who had pathologic 18F-FDG PET/CT at diagnosis repeated the examination after neoadjuvant chemotherapy, before, second look surgery. In 5 cases, no pathologic uptake was evident. Histology showed necrosis alone in 4 cases and necrosis and mature teratoma in 1. In 3 of the 6 cases with pathologic uptake (2 of 6 patients did not perform the examination at diagnosis), histology showed persistence of malignant component, whereas in the remaining 3 cases, necrosis and mature teratoma were present.

CONCLUSION

In our review of a series of children with mGCT, 18F-FDG PET/CT after neoadjuvant chemotherapy showed 1 of 5 false negatives and was unable to discriminate between residual malignant component and mature teratoma.

Construction of a predictive model for bone metastasis from first primary lung adenocarcinoma within 3 cm based on machine learning algorithm: a retrospective study

Background

Adenocarcinoma, the most prevalent histological subtype of non-small cell lung cancer, is associated with a significantly higher likelihood of bone metastasis compared to other subtypes. The presence of bone metastasis has a profound adverse impact on patient prognosis. However, to date, there is a lack of accurate bone metastasis prediction models. As a result, this study aims to employ machine learning algorithms for predicting the risk of bone metastasis in patients.

Method

We collected a dataset comprising 19,454 cases of solitary, primary lung adenocarcinoma with pulmonary nodules measuring less than 3 cm. These cases were diagnosed between 2010 and 2015 and were sourced from the Surveillance, Epidemiology, and End Results (SEER) database. Utilizing clinical feature indicators, we developed predictive models using seven machine learning algorithms, namely extreme gradient boosting (XGBoost), logistic regression (LR), light gradient boosting machine (LightGBM), Adaptive Boosting (AdaBoost), Gaussian Naive Bayes (GNB), multilayer perceptron (MLP) and support vector machine (SVM).

Results

The results demonstrated that XGBoost exhibited superior performance among the four algorithms (training set: AUC: 0.913; test set: AUC: 0.853). Furthermore, for convenient application, we created an online scoring system accessible at the following URL: https://www.xsmartanalysis.com/model/predict/?mid=731symbol=7Fr16wX56AR9Mk233917, which is based on the highest performing model.

Conclusion

XGBoost proves to be an effective algorithm for predicting the occurrence of bone metastasis in patients with solitary, primary lung adenocarcinoma featuring pulmonary nodules below 3 cm in size. Moreover, its robust clinical applicability enhances its potential utility.

Consensus recommendations in the management of Ewing sarcoma from the National Ewing Sarcoma Tumor Board

Ewing sarcoma (ES) is a malignant tumor of bone and soft tissue that most often occurs in adolescents and young adults. Despite an international coordinated approach, several nuances, discrepancies, and debates remain in defining the standard of care for treating ES. In this review, the authors leverage the expertise assembled by formation of the National Ewing Sarcoma Tumor Board, a multi-institution, multidisciplinary virtual tumor board that meets monthly to discuss complicated and challenging cases of ES. This report is focused on select topics that apply to the management of patients with newly diagnosed ES. The specific topics covered include indications for bone marrow aspirate and biopsy for initial evaluation compared with fluorodeoxyglucose-positron emission tomography, the role of interval compressed chemotherapy in patients aged 18 years and older, the role of adding ifosfamide/etoposide to vincristine/doxorubicin/cyclophosphamide for patients with metastatic disease, the data on and role of high-dose chemotherapy with autologous stem cell transplantation, maintenance therapy, and whole-lung irradiation. The data referenced are often limited to subgroup analyses and/or compiled from multiple sources. Although not intended to replace the clinical judgement of treating physicians, the guidelines are intended to provide clarity and recommendations for the upfront management of patients with ES. PLAIN LANGUAGE SUMMARY: Ewing sarcoma is a malignant tumor of bone and soft tissue that most often occurs in adolescents and young adults. For this review, the authors used the experience of the National Ewing Sarcoma Tumor Board, a multi-institution, multidisciplinary virtual tumor board that meets monthly to discuss complicated and challenging cases of Ewing sarcoma. Although not intended to replace the clinical judgement of treating physicians, the guidelines will focus on the development of consensus statements for the upfront management of patients with Ewing sarcoma.

Imaging of pediatric bone tumors: A COG Diagnostic Imaging Committee/SPR Oncology Committee White Paper

Malignant primary bone tumors are uncommon in the pediatric population, accounting for 3%-5% of all pediatric malignancies. Osteosarcoma and Ewing sarcoma comprise 90% of malignant primary bone tumors in children and adolescents. This paper provides consensus-based recommendations for imaging in children with osteosarcoma and Ewing sarcoma at diagnosis, during therapy, and after therapy.

The Impact of PET/CT on Paediatric Oncology

This review paper will discuss the use of positron emission tomography/computed tomography (PET/CT) in paediatric oncology. Functional imaging with PET/CT has proven useful to guide treatment by accurately staging disease and limiting unnecessary treatments by determining the metabolic response to treatment. 18F-Fluorodeoxyglucose (2-[18F]FDG) PET/CT is routinely used in patients with lymphoma. We highlight specific considerations in the paediatric population with lymphoma. The strengths and weaknesses for PET/CT tracers that compliment Meta-[123I]iodobenzylguanidine ([123I]mIBG) for the imaging of neuroblastoma are summarized. 2-[18F]FDG PET/CT has increasingly been used in the staging and evaluation of disease response in sarcomas. The current recommendations for the use of PET/CT in sarcomas are given and potential future developments and highlighted. 2-[18F]FDG PET/CT in combination with conventional imaging is currently the standard for disease evaluation in children with Langerhans-cell Histiocytosis (LCH) and the non-LCH disease spectrum. The common pitfalls of 2-[18F]FDG PET/CT in this setting are discussed.

Staging of newly diagnosed Ewing sarcoma: Results of bone marrow aspiration and biopsy versus (18)FDG-PET/CT imaging for bone marrow involvement

BACKGROUND

Ewing sarcoma (ES) is an aggressive bone or extraosseous tumour with an unfavourable prognosis when bone marrow metastases are present at diagnosis. The gold standard diagnosis for bone marrow (BM) involvement is cytological and pathological analysis through bone marrow aspiration and biopsy (BMAB). Several recent studies suggest that these invasive and painful procedures could be replaced by 18F-fluorodeoxyglucose-positron emission tomography/computed tomography ((18)FDG-PET/CT), as this nuclear imaging technique is highly sensitive at detecting bone and extraosseous metastases of ES.

METHODS

In order to study the precision of (18)FDG-PET/CT in the evaluation of bone marrow metastases at diagnosis, we compared the imaging results with cytological/histological analyses performed on BM samples. We retrospectively studied 180 patients with ES recorded at the Léon Bérard Centre over the past 10 years, who were evaluated by (18)FDG-PET/CT and BMAB at diagnosis.

RESULTS

Of the 180 patients, 13 displayed marrow metastases by cytological/histological examination, and only one of these did not have (18)FDG-PET/CT signs of bone marrow involvement, whereas the 167 remaining patients without marrow metastasis all had a negative (18)FDG-PET/CT, except for one. Hence, the sensitivity and specificity of (18)FDG-PET/CT in these patients was 92.3% and 99.4%, respectively. The overall survival at five years of all patients was 67.4% but decrease to 38.5% in the group with bone marrow metastases.

CONCLUSION

Given the results presented herein the bone sarcoma group of the French Sarcoma Group suggests that invasive BMAB no longer be systematically performed for the staging at the diagnosis of ES.

Management of Primary Aggressive Tumors of the Knee

Primary bone sarcomas and aggressive benign bone tumors are relatively rare. It is essential to recognize features that are concerning for these aggressive tumors based on a patient's history, physical exam, and radiographs. Physicians and other health care providers should have a high suspicion for these tumors and promptly refer these patients to orthopaedic oncologists. A multidisciplinary, team-based approach is required to obtain an accurate diagnosis and provide comprehensive care. This review discussed the appropriate work-up, biopsy principles, relevant peri-operative medical management, and surgical treatment options for patients with aggressive primary bone tumors around the knee. Primary bone sarcomas (osteosarcoma and chondrosarcoma) and aggressive benign bone tumors (giant cell tumor, chondroblastoma, and chondromyxoid fibroma) that have a predilection to the distal femur and proximal tibia are the focus of this review.

Clinical Perspectives for 18F-FDG PET Imaging in Pediatric Oncology: Μetabolic Tumor Volume and Radiomics

Pediatric cancer, although rare, requires the most optimized treatment approach to obtain high survival rates and minimize serious long-term side effects in early adulthood. 18F-FDG PET/CT is most helpful and widely used in staging, recurrence detection, and response assessment in pediatric oncology. The well-known 18F-FDG PET metabolic indices of metabolic tumor volume (MTV) and tumor lesion glycolysis (TLG) have already revealed an independent significant prognostic value for survival in oncologic patients, although the corresponding cut-off values remain study-dependent and not validated for use in clinical practice. Advanced tumor “radiomic” analysis sheds new light into these indices. Numerous patterns of texture 18F-FDG uptake features can be extracted from segmented PET tumor images due to new powerful computational systems supporting complex “deep learning” algorithms. This high number of “quantitative” tumor imaging data, although not decrypted in their majority and once standardized for the different imaging systems and segmentation methods, could be used for the development of new “clinical” models for specific cancer types and, more interestingly, for specific age groups. In addition, data from novel techniques of tumor genome analysis could reveal new genes as biomarkers for prognosis and/or targeted therapies in childhood malignancies. Therefore, this ever-growing information of “radiogenomics”, in which the underlying tumor “genetic profile” could be expressed in the tumor-imaging signature of “radiomics”, possibly represents the next model for precision medicine in pediatric cancer management. This paper reviews 18F-FDG PET image segmentation methods as applied to pediatric sarcomas and lymphomas and summarizes reported findings on the values of metabolic and radiomic features in the assessment of these pediatric tumors.

Skip metastases in high-grade intramedullary appendicular osteosarcoma: an indicator of more aggressive disease?

OBJECTIVE

To determine whether skip metastases (SM) in high-grade appendicular osteosarcoma (HG-OS) are an indicator of more aggressive disease.

MATERIALS AND METHOD

Retrospective review of patients with histologically confirmed diagnosis HG-OS of the long bones from 2007 to 2020, who had whole-bone MRI to identify SM. Data collected included patient age/gender, bone involved, the presence of SM, the presence of lung metastases from chest CT, the presence of distant bone metastases from whole-body bone scintigraphy or whole-body MRI, and chemotherapy response from resection specimen histology. The presence of lung or bone metastases and chemotherapy response were compared between patients without and with SM.

RESULTS

The study included 241 patients (146 males; 95 females: mean age 18.2 years; range 4-73 years). Based on whole-bone MRI, 202 (83.8%) patients had no SM and 39 (16.2%) patients had a SM. Of patients without a SM, lung metastases were identified in 44 (22%) and distant bone metastases in 6 (3%) cases, while 80 (43%) had a good chemotherapy response and 105 (57%) had a poor chemotherapy response. Of patients with a SM, lung metastases were identified in 22 (58%) and distant bone metastases in 8 (21%) cases, while 11 (32%) had a good chemotherapy response and 23 (68%) had a poor chemotherapy response. The presence of SM was significantly associated with both lung metastases (p < 0.001) and skeletal metastases (p < 0.001), but not with chemotherapy response (p = 0.24). Patients with SM also had poorer survival (p < 0.001).

CONCLUSIONS

The presence of SM in appendicular HG-OS suggests more aggressive disease.