Imaging changes with or without neurological symptoms after proton therapy in pediatric posterior fossa tumors; initial experience of the Dutch national cohort.

Background And Purpose: The incidence of proton therapy (PT)-related imaging changes in the central nervous system, and associated symptoms, varies widely in literature. The aim of this study was to assess imaging changes after implementation of intensity-modulated pencil beam scanning in a national cohort of pediatric posterior fossa (PF) tumors.

Materials And Methods: All pediatric PF tumor patients treated in the XXX with PT between 06-2018 and 12-2022 were analyzed.

Gross tumor volume increase and need for adaptive radiotherapy in pediatric-type diffuse high-grade glioma of the midline structures.

Introduction: Current pediatric-type diffuse high-grade glioma radiotherapy protocols apply a 1.0 cm clinical target volume (CTV) margin around the gross tumor volume (GTV). However, in adults with glioblastoma, large variations in GTV are observed during radiotherapy.

Rationale, implementation considerations, delineation and planning target objective recommendations for volumetric modulated arc therapy and helical tomotherapy total body irradiation, total marrow irradiation, total marrow and lymphoid irradiation and total lymphoid irradiation.

As a component of myeloablative conditioning before allogeneic hematopoietic stem cell transplantation (HSCT), Total Body Irradiation (TBI) is employed in radiotherapy centers all over the world. In recent and coming years, many centers are changing their TBI setup to a conformal isocentric technique, providing superior homogeneity and control of the target prescription dose, and more freedom for individualized organ-at-risk sparing or dose-escalation. Also, more specifically bone-marrow- and/or lymphatics-targeted therapies such as Total Marrow (+ Lymphoid) Irradiation (TMI / TMLI), and Total Lymphoid Irradiation (TLI) are established and prospectively evaluated in several centers.

Technical recommendations for implementation of Volumetric Modulated Arc Therapy and Helical Tomotherapy Total Body Irradiation.

As a component of myeloablative conditioning before allogeneic hematopoietic stem cell transplantation (HSCT), Total Body Irradiation (TBI) is employed in radiotherapy centers all over the world. In recent and coming years, many centers are changing their technical setup from a conventional TBI technique to multi-isocenter conformal arc therapy techniques such as Volumetric Modulated Arc Therapy (VMAT) or Helical Tomotherapy (HT). These techniques allow better homogeneity and control of the target prescription dose, and provide more freedom for individualized organ-at-risk sparing.

ESTRO ACROP and SIOPE recommendations for myeloablative Total Body Irradiation in children.

Background And Purpose: Myeloablative Total Body Irradiation (TBI) is an important modality in conditioning for allogeneic hematopoietic stem cell transplantation (HSCT), especially in children with high-risk acute lymphoblastic leukemia (ALL). TBI practices are heterogeneous and institution-specific. Since TBI is associated with multiple late adverse effects, recommendations may help to standardize practices and improve the outcome versus toxicity ratio for children.

Progress against non-Hodgkin's lymphoma in children and young adolescents in the Netherlands since 1990: Stable incidence, improved survival and lower mortality.

Background: With epidemiologic analyses of population-based trends in incidence and outcomes, we ascertained progress against non-Hodgkin's lymphoma (NHL) in children and young adolescents in the Netherlands since 1990.

Methods: Tumour characteristics were extracted from the Netherlands Cancer Registry for patients aged <18 years at diagnosis, between 1990 and 2015. Mortality data for 1980-2016 were derived from Statistics Netherlands.

Novel VHH-Based Tracers with Variable Plasma Half-Lives for Imaging of CAIX-Expressing Hypoxic Tumor Cells.

Hypoxic areas are present in the majority of solid tumors, and hypoxia is associated with resistance to therapies and poor outcomes. A transmembrane protein that is upregulated by tumor cells that have adapted to hypoxic conditions is carbonic anhydrase IX (CAIX). Therefore, noninvasive imaging of CAIX could be of prognostic value, and it could steer treatment strategies.

A Review of Acute and Long-Term Neurological Complications Following Haematopoietic Stem Cell Transplant for Paediatric Acute Lymphoblastic Leukaemia.

Despite advances in haematopoietic stem cell transplant (HSCT) techniques, the risk of serious side effects and complications still exists. Neurological complications, both acute and long term, are common following HSCT and contribute to significant morbidity and mortality. The aetiology of neurotoxicity includes infections and a wide variety of non-infectious causes such as drug toxicities, metabolic abnormalities, irradiation, vascular and immunologic events and the leukaemia itself.

Total Body Irradiation in Haematopoietic Stem Cell Transplantation for Paediatric Acute Lymphoblastic Leukaemia: Review of the Literature and Future Directions.

Total body irradiation (TBI) has been a pivotal component of the conditioning regimen for allogeneic myeloablative haematopoietic stem cell transplantation (HSCT) in very-high-risk acute lymphoblastic leukaemia (ALL) for decades, especially in children and young adults. The myeloablative conditioning regimen has two aims: (1) to eradicate leukaemic cells, and (2) to prevent rejection of the graft through suppression of the recipient's immune system. Radiotherapy has the advantage of achieving an adequate dose effect in sanctuary sites and in areas with poor blood supply.

Late Effects After Haematopoietic Stem Cell Transplantation in ALL, Long-Term Follow-Up and Transition: A Step Into Adult Life.

Haematopoietic stem cell transplant (HSCT) can be a curative treatment for children and adolescents with very-high-risk acute lymphoblastic leukaemia (ALL). Improvements in supportive care and transplant techniques have led to increasing numbers of long-term survivors worldwide. However, conditioning regimens as well as transplant-related complications are associated with severe sequelae, impacting patients' quality of life.

Influence of eye movement on lens dose and optic nerve target coverage during craniospinal irradiation.

Purpose: Optic nerves are part of the craniospinal irradiation (CSI) target volume. Modern radiotherapy techniques achieve highly conformal target doses while avoiding organs-at-risk such as the lens. The magnitude of eye movement and its influence on CSI target- and avoidance volumes are unclear.

Imaging carbonic anhydrase IX as a method for monitoring hypoxia-related radioresistance in preclinical head and neck cancer models.

Background And Purpose: Tumor hypoxia is an important cause of radioresistance and is associated with poor outcome.SPECT (Single-photon emission computed tomography) imaging enables visualizing tumor characteristics. We investigated the SPECT-radiotracer [In]-girentuximab-F(ab') to image Carbonic Anhydrase IX (CAIX), an enzyme upregulated under hypoxic conditions.

Inter-clinician delineation variation for a new highly-conformal flank target volume in children with renal tumors: A SIOP-Renal Tumor Study Group international multicenter exercise.

Background And Purpose: Recently, the SIOP-RTSG developed a highly-conformal flank target volume definition for children with renal tumors. The aims of this study were to evaluate the inter-clinician delineation variation of this new target volume definition in an international multicenter setting and to explore the necessity of quality assurance.

Materials And Methods: Six pediatric renal cancer cases were transferred to ten radiation oncologists from seven European countries ('participants').

Towards homogenization of total body irradiation practices in pediatric patients across SIOPE affiliated centers. A survey by the SIOPE radiation oncology working group.

Background And Purpose: To reduce relapse risk, Total Body Irradiation (TBI) is part of conditioning regimens for hematopoietic stem cell transplantation (HSCT) in pediatric acute leukemia. The study purpose was to evaluate clinical practices regarding TBI, such as fractionation, organ shielding and delivery techniques, among SIOPE affiliated radiotherapy centers.

Methods: An electronic survey was sent out to 233 SIOPE affiliated centers, containing 57 questions about clinical practice of TBI.

CAIX-targeting radiotracers for hypoxia imaging in head and neck cancer models.

Hypoxia-induced carbonic anhydrase IX (CAIX) expression is a prognostic marker in solid tumors. In recent years many radiotracers have been developed, but a fair comparison of these compounds is not possible because of the diversity in tumor models and other experimental parameters. In this study we performed a direct in vivo comparison of three promising CAIX targeting radiotracers in xenografted head and neck cancer models.

F-FDG-PET/CT-based treatment planning for definitive (chemo)radiotherapy in patients with head and neck squamous cell carcinoma improves regional control and survival.

Background And Purpose: Multimodality imaging including F-FDG-PET has improved the detection threshold of nodal metastases in head and neck squamous cell carcinoma (HNSCC). The aim of this retrospective analysis is to investigate the impact of FDG-PET/CT-based nodal target volume definition (FDG-PET/CT-based NTV) on radiotherapy outcomes, compared to conventional CT-based nodal target volume definition (CT-based NTV).

Materials And Methods: Six-hundred-thirty-three patients treated for HNSCC with definitive (chemo)radiotherapy using IMRT/VMAT techniques between 2008 and 2017 were analyzed.

Quantitative Imaging of the Hypoxia-Related Marker CAIX in Head and Neck Squamous Cell Carcinoma Xenograft Models.

Tumor hypoxia plays a major role in radio- and chemotherapy resistance in solid tumors. Carbonic Anhydrase IX (CAIX) is an endogenous hypoxia-related protein, which is associated with poor patient outcome. The quantitative assessment of CAIX expression of tumors may steer cancer treatment by predicting therapy response or patient selection for antihypoxia or CAIX-targeted treatment.

Dosimetric comparison of five different techniques for craniospinal irradiation across 15 European centers: analysis on behalf of the SIOP-E-BTG (radiotherapy working group).

Purpose: Conventional techniques (3D-CRT) for craniospinal irradiation (CSI) are still widely used. Modern techniques (IMRT, VMAT, TomoTherapy, proton pencil beam scanning [PBS]) are applied in a limited number of centers. For a 14-year-old patient, we aimed to compare dose distributions of five CSI techniques applied across Europe and generated according to the participating institute protocols, therefore representing daily practice.

Preclinical validation of In-girentuximab-F(ab') as a tracer to image hypoxia related marker CAIX expression in head and neck cancer xenografts.

Background And Purpose: Hypoxia is a major cause of radio- and chemoresistance. Carbonic anhydrase IX (CAIX) is an endogenous hypoxia-related marker and an important prognostic marker. Assessment of CAIX expression may allow patient selection for hypoxia or CAIX-targeted treatment.

Systematic analysis of 18F-FDG PET and metabolism, proliferation and hypoxia markers for classification of head and neck tumors.

Background: Quantification of molecular cell processes is important for prognostication and treatment individualization of head and neck cancer (HNC). However, individual tumor comparison can show discord in upregulation similarities when analyzing multiple biological mechanisms. Elaborate tumor characterization, integrating multiple pathways reflecting intrinsic and microenvironmental properties, may be beneficial to group most uniform tumors for treatment modification schemes.

Semiautomatic methods for segmentation of the proliferative tumour volume on sequential FLT PET/CT images in head and neck carcinomas and their relation to clinical outcome.

Purpose: Radiotherapy of head and neck cancer induces changes in tumour cell proliferation during treatment, which can be depicted by the PET tracer (18)F-fluorothymidine (FLT). In this study, three advanced semiautomatic PET segmentation methods for delineation of the proliferative tumour volume (PV) before and during (chemo)radiotherapy were compared and related to clinical outcome.

Methods: The study group comprised 46 patients with 48 squamous cell carcinomas of the head and neck, treated with accelerated (chemo)radiotherapy, who underwent FLT PET/CT prior to treatment and in the 2nd and 4th week of therapy.

Imaging of epidermal growth factor receptor expression in head and neck cancer with SPECT/CT and 111In-labeled cetuximab-F(ab')2.

Unlabelled: Combined treatment of advanced head and neck squamous cell carcinomas (HNSCC) with radiotherapy and the epidermal growth factor receptor (EGFR) inhibitor cetuximab improves clinical outcome in comparison to radiotherapy alone but is effective only in a few cases. To select those patients most likely to benefit from EGFR inhibition, it can be advantageous to quantify the tumor EGFR status before and possibly during therapy. The aim of this study was to develop and characterize the (111)In-cetuximab-F(ab')2 tracer to image EGFR targeting in vivo.

Molecular PET imaging for biology-guided adaptive radiotherapy of head and neck cancer.

Integration of molecular imaging PET techniques into therapy selection strategies and radiation treatment planning for head and neck squamous cell carcinoma (HNSCC) can serve several purposes. First, pre-treatment assessments can steer decisions about radiotherapy modifications or combinations with other modalities. Second, biology-based objective functions can be introduced to the radiation treatment planning process by co-registration of molecular imaging with planning computed tomography (CT) scans.

111In-cetuximab-F(ab')2 SPECT imaging for quantification of accessible epidermal growth factor receptors (EGFR) in HNSCC xenografts.

Background And Purpose: Immunohistochemical epidermal growth factor receptor (EGFR) expression does not correlate with treatment response in head and neck squamous cell carcinomas (HNSCC). Aim was to apply the tracer (111)In-cetuximab-F(ab')2 for EGFR microSPECT imaging and to investigate if tracer uptake correlated with response to EGFR-inhibition by cetuximab in HNSCC xenografts. Usage of F(ab)2 fragments allows for shorter interval between tracer injection and imaging.