Automatic Quantification of Serial PET/CT Images for Pediatric Hodgkin Lymphoma Patients Using a Longitudinally-Aware Segmentation Network.

Purpose: Automatic quantification of longitudinal changes in PET scans for lymphoma patients has proven challenging, as residual disease in interim-therapy scans is often subtle and difficult to detect. Our goal was to develop a longitudinally-aware segmentation network (LAS-Net) that can quantify serial PET/CT images for pediatric Hodgkin lymphoma patients. Materials and Methods: This retrospective study included baseline (PET1) and interim (PET2) PET/CT images from 297 patients enrolled in two Children's Oncology Group clinical trials (AHOD1331 and AHOD0831). LAS-Net incorporates longitudinal cross-attention, allowing relevant features from PET1 to inform the analysis of PET2. Model performance was evaluated using Dice coefficients for PET1 and detection F1 scores for PET2. Additionally, we extracted and compared quantitative PET metrics, including metabolic tumor volume (MTV) and total lesion glycolysis (TLG) in PET1, as well as qPET and ΔSUVmax in PET2, against physician measurements. We quantified their agreement using Spearman's ρ correlations and employed bootstrap resampling for statistical analysis. Results: LAS-Net detected residual lymphoma in PET2 with an F1 score of 0.606 (precision/recall: 0.615/0.600), outperforming all comparator methods (P<0.01). For baseline segmentation, LAS-Net achieved a mean Dice score of 0.772. In PET quantification, LAS-Net's measurements of qPET, ΔSUVmax, MTV and TLG were strongly correlated with physician measurements, with Spearman's ρ of 0.78, 0.80, 0.93 and 0.96, respectively. The performance remained high, with a slight decrease, in an external testing cohort. Conclusion: LAS-Net achieved high performance in quantifying PET metrics across serial scans, highlighting the value of longitudinal awareness in evaluating multi-time-point imaging datasets.

Pulmonary lesions in early response assessment in pediatric Hodgkin lymphoma: prevalence and possible implications for initial staging.

BACKGROUND: Disseminated pulmonary involvement in pediatric Hodgkin lymphoma (pHL) is indicative of Ann Arbor stage IV disease. During staging, it is necessary to assess for coexistence of non-malignant lung lesions due to infection representing background noise to avoid erroneously upstaging with therapy intensification. OBJECTIVE: This study attempts to describe new lung lesions detected on interim staging computed tomography (CT) scans after two cycles of vincristine, etoposide, prednisolone, doxorubicin in a prospective clinical trial. Based on the hypothesis that these new lung lesions are not part of the underlying malignancy but are epiphenomena, the aim is to analyze their size, number, and pattern to help distinguish true lung metastases from benign lung lesions on initial staging. MATERIALS AND METHODS: A retrospective analysis of the EuroNet-PHL-C1 trial re-evaluated the staging and interim lung CT scans of 1,300 pediatric patients with HL. Newly developed lung lesions during chemotherapy were classified according to the current Fleischner glossary of terms for thoracic imaging. Patients with new lung lesions found at early response assessment (ERA) were additionally assessed and compared to response seen in hilar and mediastinal lymph nodes. RESULTS: Of 1,300 patients at ERA, 119 (9.2%) had new pulmonary lesions not originally detectable at diagnosis. The phenomenon occurred regardless of initial lung involvement or whether a patient relapsed. In the latter group, new lung lesions on ERA regressed by the time of relapse staging. New lung lesions on ERA in patients without relapse were detected in 102 (7.8%) patients. Pulmonary nodules were recorded in 72 (5.5%) patients, the majority (97%) being<10 mm. Consolidations, ground-glass opacities, and parenchymal bands were less common. CONCLUSION: New nodules on interim staging are common, mostly measure less than 10 mm in diameter and usually require no further action because they are most likely non-malignant. Since it must be assumed that benign and malignant lung lesions coexist on initial staging, this benign background noise needs to be distinguished from lung metastases to avoid upstaging to stage IV disease. Raising the cut-off size for lung nodules to ≥ 10 mm might achieve the reduction of overtreatment but needs to be further evaluated with survival data. In contrast to the staging criteria of EuroNet-PHL-C1 and C2, our data suggest that the number of lesions present at initial staging may be less important.

Significance of E-lesions in Hodgkin lymphoma and the creation of a new consensus definition: a report from SEARCH.

The International Staging Evaluation and Response Criteria Harmonization for Childhood, Adolescent, and Young Adult Hodgkin Lymphoma (SEARCH for CAYAHL) seeks to provide an appropriate, universal differentiation between E-lesions and stage IV extranodal disease in Hodgkin lymphoma (HL). A literature search was performed through the PubMed and Google Scholar databases using the terms "Hodgkin disease," and "extranodal," "extralymphatic," "E lesions," "E stage," or "E disease." Publications were reviewed for the number of participants; median age and age range; diagnostic modalities used for staging; and the definition, incidence, and prognostic significance of E-lesions. Thirty-six articles describing 12 640 patients met the inclusion criteria. Most articles reported staging per the Ann Arbor (72%, 26/36) or Cotswolds modification of the Ann Arbor staging criteria (25%, 9/36), and articles rarely defined E-lesions or disambiguated "extranodal disease." The overall incidence of E-lesions for patients with stage I-III HL was 11.5% (1330/11 602 unique patients). Available stage-specific incidence analysis of 3888 patients showed a similar incidence of E-lesions in stage II (21.2%) and stage III (21.9%), with E-lesions rarely seen with stage I disease (1.1%). E-lesions likely remain predictive, but we cannot unequivocally conclude that identifying E-lesions in HL imparts prognostic value in the modern era of the more selective use of targeted radiation therapy. A harmonized E-lesion definition was reached based on the available evidence and the consensus of the SEARCH working group. We recommend that this definition of E-lesion be applied in future clinical trials with explicit reporting to confirm the prognostic value of E-lesions.

Prognostic value of chest x-ray- and CT-defined large mediastinal adenopathy in high-risk pediatric Hodgkin lymphoma: A report from the Children's Oncology Group Study AHOD0831.

PURPOSE/OBJECTIVE: We compared the prognostic value of chest radiograph (CXR)- and computed tomography (CT)-derived definition of large mediastinal adenopathy (LMA) in pediatric Hodgkin lymphoma (HL). MATERIALS/METHODS: Total 143 patients treated for stage IIIB/IVB HL on COG AHOD0831 were included in this study. Six definitions of LMA were investigated: (i) mediastinal mass ratio on CXR (MRCXR ) > 1/3; (ii) mediastinal mass ratio on CT (MRCT ) > 1/3; (iii) mediastinal mass volume on CT (MVCT ) > 200 mL; (iv) normalized mediastinal mass volume (MVCT /thoracic diameter [TD]) > 1 mL/mm; (v) mediastinal mass diameter on CT (MDCT ) > 10 cm; and (vi) normalized mediastinal mass diameter (MDCT /TD) > 1/3. RESULTS: Median age at diagnosis was 15.8 years (range: 5.2-21.3 years). In patients with a slow early response (SER) to chemotherapy, MVCT  > 200 mL, MDCT  > 10 cm, and MDCT /TD > 1/3 were associated with worse relapse-free survival (RFS) on MVA, while MRCXR  > 1/3, MRCT  > 1/3, and MVCT /TD > 1 mL/mm trended toward worse RFS; MDCT /TD was the most strongly prognostic for inferior RFS, with a hazard ratio of 6.41 for MDCT /TD > 1/3 versus ≤1/3 on MVA (p = .02). CONCLUSION: LMA according to MVCT  > 200 mL, MDCT  > 10 cm, and MDCT /TD > 1/3 is associated with poor prognosis in advanced-stage HL patients with SER. The normalized mediastinal diameter, MDCT /TD > 1/3 appears to be the strongest predictor of inferior RFS.

Importance of Central Imaging Review in a Pediatric Hodgkin Lymphoma Trial Using Positron Emission Tomography Response Adapted Radiation Therapy.

PURPOSE: We investigated the effects of central review of the interim fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) scan response (iPET) assessment on treatment allocation in the risk-based, response-adapted, Children's Oncology Group study AHOD1331 (ClinicalTrials.gov identifier: NCT02166463) for pediatric patients with high-risk Hodgkin lymphoma. METHODS AND MATERIALS: Per protocol, after 2 cycles of systemic therapy, patients underwent iPET, with visual response assessment by 5-point Deauville score (DS) at their treating institution and a real-time central review, with the latter considered the reference standard. An area of disease with a DS of 1 to 3 was considered a rapid-responding lesion, whereas a DS of 4 to 5 was considered a slow-responding lesion (SRL). Patients with 1 or more SRLs were considered iPET positive, whereas patients with only rapid-responding lesions were considered iPET negative. We conducted a predefined exploratory evaluation of concordance in iPET response assessment between institutional and central reviews of 573 patients. The concordance rate was evaluated using the Cohen κ statistic (κ > 0.80 was considered very good agreement and κ > 0.60-0.80, good agreement). RESULTS: The concordance rate (514 of 573 [89.7%]) had a κ of 0.685 (95% CI, 0.610-0.759), consistent with good agreement. In terms of the direction of discordance, among the 126 patients who were considered iPET positive by institutional review, 38 (30.2%) were categorized as iPET negative by central review, preventing overtreatment with radiation therapy. Conversely, among the 447 patients who were considered iPET negative by institutional review, 21 patients (4.7%) were categorized as iPET positive by the central review and would have been undertreated without radiation therapy. CONCLUSIONS: Central review is integral to PET response-adapted clinical trials for children with Hodgkin lymphoma. Continued support of central imaging review and education about DS are needed.

Baseline metabolic tumour burden improves risk stratification in Hodgkin lymphoma: A Children's Oncology Group study.

The Children's Oncology Group AHOD0831 study used a positron emission tomography (PET) response-adapted approach in high-risk Hodgkin lymphoma, whereby slow early responders (SERs) received more intensive therapy than rapid early responders (RERs). We explored if baseline PET-based characteristics would improve risk stratification. Of 166 patients enrolled in the COG AHOD0831 study, 94 (57%) had baseline PET scans evaluable for quantitative analysis. For these patients, total body metabolic tumour volume (MTV), total lesion glycolysis (TLG), maximum standardized uptake value (SUVmax ) and peak SUV (SUVpeak ) were obtained. MTV/TLG thresholds were an SUV of 2.5 (MTV2.5 /TLG2.5 ) and 40% of the tumour SUVmax (MTV40% /TLG40% ). TLG2.5 was associated with event-free survival (EFS) in the complete cohort (p = 0.04) and in RERs (p = 0.01), but not in SERs (p = 0.8). The Youden index cut-off for TLG2.5 was 1841. Four-year EFS was 92% for RER/TLG2.5  up to 1841, 60% for RER/TLG2.5  greater than 1841, 74% for SER/TLG2.5  up to 1841 and 79% for SER/TLG2.5  greater than 1841. Second EFS for RER/TLG2.5  up to 1841 was 100%. Thus, RERs with a low baseline TLG2.5 experienced excellent EFS with less intensive therapy, whereas RERs with a high baseline TLG2.5 experienced poor EFS. These findings suggest that patients with a high upfront tumour burden may benefit from intensified therapy, even if they achieve a RER.

Imaging recommendations in pediatric lymphoma: A COG Diagnostic Imaging Committee/SPR Oncology Committee White Paper.

Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL) are both malignancies originating in the lymphatic system and both affect children, but many features differ considerably, impacting workup and management. This paper provides consensus-based imaging recommendations for evaluation of patients with HL and NHL at diagnosis and response assessment for both interim and end of therapy (follow-up).

Selective Skeletal Surveys for Infants With Skull Fractures: Examining the Rates of Return to Medical Care for Concern of Physical Abuse.

OBJECTIVES: This study aimed to describe which infants with a skull fracture (1) receive a child abuse pediatrician (CAP) consultation, (2) receive a skeletal survey, and (3) re-present to medical care before age 3 years with concerns for physical abuse. METHODS: We conducted a retrospective chart review of infants younger than 12 months who presented to the emergency department between January 1, 2005, and December 30, 2015, with a skull fracture. Medical records were reviewed for the skull fracture presentation and for all future medical evaluations at the same institution with concerns for physical abuse until 3 years of age. RESULTS: Of 366 infants with a skull fracture, a CAP was contacted for 272 (74%) and 76 (20.8%) infants who received a skeletal survey. Factors associated with skeletal survey acquisition included younger age (<6 months), no history to explain the skull fracture, other injuries on examination, and social risk factors. Six children (1.6%) re-presented to medical care with concerns of physical abuse before age 3 years. Five of these infants did not have a skeletal survey at the time of their skull fracture, and 1 was likely a case of missed physical abuse at the time of the skull fracture. DISCUSSION: Most skull fractures in infancy occur accidentally, and a skeletal survey may not be necessary for every infant. Obtaining a thorough history including social risk factors, performing a complete physical examination, and consulting with a CAP is an effective first step in the evaluation of physical abuse in infants with skull fractures.

Brentuximab Vedotin with Chemotherapy in Pediatric High-Risk Hodgkin's Lymphoma.

BACKGROUND: In adults with advanced-stage Hodgkin's lymphoma, the CD30-directed antibody-drug conjugate brentuximab vedotin combined with multiagent chemotherapy has been shown to have greater efficacy, but also more toxic effects, than chemotherapy alone. The efficacy of this targeted therapy approach in children and adolescents with Hodgkin's lymphoma is unclear. METHODS: We conducted an open-label, multicenter, randomized, phase 3 trial involving patients 2 to 21 years of age with previously untreated Hodgkin's lymphoma of stage IIB with bulk tumor or stage IIIB, IVA, or IVB. Patients were assigned to receive five 21-day cycles of brentuximab vedotin with doxorubicin, vincristine, etoposide, prednisone, and cyclophosphamide (brentuximab vedotin group) or the standard pediatric regimen of doxorubicin, bleomycin, vincristine, etoposide, prednisone, and cyclophosphamide (standard-care group). Slow-responding lesions, defined by a score of 4 or 5 (on a 5-point scale, with scores of 1 to 3 indicating rapid-responding lesions), were identified on centrally reviewed positron-emission tomography-computed tomography after two cycles. Involved-site radiation therapy was administered after the fifth cycle of therapy to slow-responding lesions and to large mediastinal adenopathy that was present at diagnosis. The primary end point was event-free survival, defined as the time until disease progression occurred, relapse occurred, a second malignant neoplasm developed, or the patient died. Safety and overall survival were assessed. RESULTS: Of 600 patients who were enrolled across 153 institutions, 587 were eligible. At a median follow-up of 42.1 months (range, 0.1 to 80.9), the 3-year event-free survival was 92.1% (95% confidence interval [CI], 88.4 to 94.7) in the brentuximab vedotin group, as compared with 82.5% (95% CI, 77.4 to 86.5) in the standard-care group (hazard ratio for event or death, 0.41; 95% CI, 0.25 to 0.67; P<0.001). The percentage of patients who received involved-site radiation therapy did not differ substantially between the brentuximab vedotin group and the standard-care group (53.4% and 56.8%, respectively). Toxic effects were similar in the two groups. Overall survival at 3 years was 99.3% (95% CI, 97.3 to 99.8) in the brentuximab vedotin group and 98.5% (95% CI, 96.0 to 99.4) in the standard-care group. CONCLUSIONS: The addition of brentuximab vedotin to standard chemotherapy resulted in superior efficacy, with a 59% lower risk of an event or death, and no increase in the incidence of toxic effects at 3 years. (Funded by the National Institutes of Health and others; AHOD1331 ClinicalTrials.gov number, NCT02166463.).

Targeted radiotherapy for early-stage, low-risk pediatric Hodgkin lymphoma slow early responders: a COG AHOD0431 analysis.

Children's Oncology Group (COG) trial AHOD0431 reduced systemic therapy and used response-adapted involved-field radiotherapy (IFRT) in early-stage pediatric classic Hodgkin lymphoma. We investigated the impact of positron emission tomographic response after 1 cycle (PET1) and on IFRT outcomes and pattern of relapse. Patients in AHOD0431 underwent PET1 response assessment after AVPC (doxorubicin, vincristine, prednisone, and cyclophosphamide). "Rapid early responders" (RERs) had a negative PET1 (PET1-); "slow early responders" (SERs) had a positive PET1 (PET1+). Patients with a partial response by computed tomographic and functional imaging after 3 chemotherapy cycles received 21-Gy IFRT, whereas complete responders had no IFRT. Progression-free survival (PFS) was evaluated for RERs and SERs treated with or without IFRT. Recurrence sites were initial, new, or both. Relapses involving initial sites were characterized as "within the PET1+ site" or "initially involved but outside the PET1+ site." Median follow-up was 118 months. The 10-year PFS rate among RERs was 96.6% with IFRT and 84.1% without IFRT (P = .10), whereas SERs were 80.9% with IFRT and 64.0% without IFRT (P = .03). Among 90 RERs who did not receive IFRT, all 14 relapses included an initial site. Among 45 SERs receiving no IFRT, 14 of 16 relapses were in the initial site (9 PET1+ site only). Among 58 patients receiving IFRT, 5 of 10 relapses were in the PET1+ site. After 3 cycles of AVPC alone, RERs showed favorable results. Conversely, SERs had unfavorable outcomes with AVPC alone, although they improved with 21-Gy IFRT. RT remains an important component of treatment for SERs. This trial was registered at www.clinicaltrials.gov as #NCT00302003.

Durable remission for four pediatric patients with high-risk relapsed classical Hodgkin lymphoma treated with brentuximab vedotin plus gemcitabine but without autologous stem cell transplantation: A report from the Children's Oncology Group.

Patients with therapy-refractory or high-risk relapsed classical Hodgkin lymphoma are typically treated with the high-dose chemotherapy and autologous stem cell transplantation (HDC/ASCT) to consolidate the response to salvage therapy. The combination of brentuximab vedotin with gemcitabine has recently been shown to be an effective and safe salvage regimen. While the majority of patients with complete responses to this regimen ultimately underwent HDC/ASCT consolidation, four subjects, reported herein, achieved durable complete remissions lasting more than 4 years after the study treatment but without ASCT consolidation. Further investigation of treatment strategies incorporating targeted agents may allow omission of HDC/ASCT for select patients.

Patterns of Initial Relapse from a Phase 3 Study of Response-Based Therapy for High-Risk Hodgkin Lymphoma (AHOD0831): A Report from the Children's Oncology Group.

PURPOSE: The Children's Oncology Group protocol AHOD0831, for pediatric patients with high-risk classical Hodgkin lymphoma (cHL), used response-adapted radiation fields, rather than larger involved-field radiation therapy (IFRT) that were historically used. This retrospective analysis of patterns of relapse among patients enrolled in the study was conducted to study the potential effect of a reduction in RT exposure. METHODS AND MATERIALS: From December 2009 to January 2012, 164 eligible patients under 22 years old with stage IIIB (43%) and stage IVB (57%) enrolled on AHOD0831. All patients received 4 cycles of doxorubicin, bleomycin, vincristine, etoposide, prednisone, and cyclophosphamide (ABVE-PC). Those patients with a slow early response (SER) after the first 2 ABVE-PC courses were nonrandomly assigned to 2 intensification cycles with ifosfamide/vinorelbine before the final 2 ABVE-PC cycles. Response-adapted RT (21 Gy) was prescribed to initial areas of bulky disease and SER sites. Rapid early response (RER) sites without bulk were not targeted. Imaging studies at the time of progression or relapse were reviewed centrally for this retrospective analysis. Relapses were characterized with respect to site (initial, new, or both; and initial bulk or initial nonbulk), initial chemotherapy response, and radiation field (in-field, out-of-field, or both). RESULTS: Of the entire cohort, 140 patients were evaluable for the patterns of failure analyses. To investigate the pattern of failure, this analysis focuses on 23 patients who followed protocol treatment and suffered relapses at a median 1.05 years with 7.97-year median follow-up time. These 23 patients (11 RER and 12 SER) experienced a relapse in 105 total sites (median, 4; range, 1-11). Of the 105 relapsed sites, 67 sites (64%) occurred within an initial site of involvement, with 12 of these 67 sites (18%) at an initial site of bulky disease and 63 of these 67 relapses (94%) occurring in sites that were not fluorodeoxyglucose (FDG)-avid after 2 cycles of ABVE-PC (PET2-negative). Of the 105 relapsed sites, 34 sites (32%) occurred in a new site of disease (that would not have been covered by RT); and, overall, only 4 of 140 patients (2.8%) (occurring in 3 RER and 1 SER) experienced isolated out-of-field relapses that would have been covered by historical IFRT. CONCLUSIONS: For a cohort of high-risk patients with cHL patients, most failures occurred in nonbulky, initially involved sites, largely due to response-based consolidation RT delivered to patients with bulky disease. In this analysis, we discovered low rates of failures outside of these modern risk-adapted radiation treatment volumes. Also, FDG uptake on PET2 did not identify most relapse sites.

Prognostic value of baseline metabolic tumor volume in children and adolescents with intermediate-risk Hodgkin lymphoma treated with chemo-radiation therapy: FDG-PET parameter analysis in a subgroup from COG AHOD0031.

BACKGROUND: Positron emission tomography (PET)-based measures of baseline total-body tumor burden may improve risk stratification in intermediate-risk Hodgkin lymphoma (HL). MATERIALS AND METHODS: Evaluable patients were identified from a cohort treated homogeneously with the same combined modality regimen on the Children's Oncology Group AHOD0031 study. Eligible patients had high-quality baseline PET scans. Metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were each measured based on 15 thresholds for every patient. Univariate and multivariable Cox regression and Kaplan-Meier survival analyses assessed for an association of MTV and TLG with event-free survival (EFS). RESULTS: From the AHOD0031 cohort (n = 1712), 86 patients were identified who (i) were treated with four cycles of doxorubicin, bleomycin, vincristine, etoposide, prednisone, cyclophosphamide (ABVE-PC) chemotherapy followed by involved field radiotherapy, and (ii) had a baseline PET scan that was amenable to quantitative analysis. Based on univariate Cox regression analysis, six PET-derived parameters were significantly associated with EFS. For each of these, Kaplan-Meier analyses and the log-rank test were used to compare patients with highest tumor burden (i.e., highest 15%) to the remainder of the cohort. EFS was significantly associated with all six PET parameters (all p < .029). In a multivariable model controlling for important covariates including disease bulk and response to chemotherapy, MTV2BP was significantly associated with EFS (p = .012). CONCLUSION: Multiple baseline PET-derived volumetric parameters were associated with EFS. MTV2BP was highly associated with EFS when controlling for disease bulk and response to chemotherapy. Incorporation of baseline MTV into risk-based treatment algorithms may improve outcomes in intermediate-risk HL.

Automated quantification of baseline imaging PET metrics on FDG PET/CT images of pediatric Hodgkin lymphoma patients.

PURPOSE: For pediatric lymphoma, quantitative FDG PET/CT imaging features such as metabolic tumor volume (MTV) are important for prognosis and risk stratification strategies. However, feature extraction is difficult and time-consuming in cases of high disease burden. The purpose of this study was to fully automate the measurement of PET imaging features in PET/CT images of pediatric lymphoma. METHODS: 18F-FDG PET/CT baseline images of 100 pediatric Hodgkin lymphoma patients were retrospectively analyzed. Two nuclear medicine physicians identified and segmented FDG avid disease using PET thresholding methods. Both PET and CT images were used as inputs to a three-dimensional patch-based, multi-resolution pathway convolutional neural network architecture, DeepMedic. The model was trained to replicate physician segmentations using an ensemble of three networks trained with 5-fold cross-validation. The maximum SUV (SUVmax), MTV, total lesion glycolysis (TLG), surface-area-to-volume ratio (SA/MTV), and a measure of disease spread (Dmaxpatient) were extracted from the model output. Pearson's correlation coefficient and relative percent differences were calculated between automated and physician-extracted features. RESULTS: Median Dice similarity coefficient of patient contours between automated and physician contours was 0.86 (IQR 0.78-0.91). Automated SUVmax values matched exactly the physician determined values in 81/100 cases, with Pearson's correlation coefficient (R) of 0.95. Automated MTV was strongly correlated with physician MTV (R = 0.88), though it was slightly underestimated with a median (IQR) relative difference of - 4.3% (- 10.0-5.7%). Agreement of TLG was excellent (R = 0.94), with median (IQR) relative difference of - 0.4% (- 5.2-7.0%). Median relative percent differences were 6.8% (R = 0.91; IQR 1.6-4.3%) for SA/MTV, and 4.5% (R = 0.51; IQR - 7.5-40.9%) for Dmaxpatient, which was the most difficult feature to quantify automatically. CONCLUSIONS: An automated method using an ensemble of multi-resolution pathway 3D CNNs was able to quantify PET imaging features of lymphoma on baseline FDG PET/CT images with excellent agreement to reference physician PET segmentation. Automated methods with faster throughput for PET quantitation, such as MTV and TLG, show promise in more accessible clinical and research applications.

Expert consensus statements for Waldeyer's ring involvement in pediatric Hodgkin lymphoma: The staging, evaluation, and response criteria harmonization (SEARCH) for childhood, adolescent, and young adult Hodgkin lymphoma (CAYAHL) group.

Waldeyer's ring (WR) involvement in pediatric Hodgkin lymphoma (HL) is extremely rare and criteria for determining involvement and response to treatment are unclear. The international Staging, Evaluation, and Response Criteria Harmonization for Childhood, Adolescent and Young Adult Hodgkin Lymphoma (SEARCH for CAYAHL) Group performed a systematic review of the literature in search of involvement or response criteria, or evidence to support specific criteria. Only 166 cases of HL with WR involvement were reported in the literature, 7 of which were pediatric. To date no standardized diagnostic or response assessment criteria are available. Given the paucity of evidence, using a modified Delphi survey technique, expert consensus statements were developed by the SEARCH group to allow for a more consistent definition of disease and response evaluation related to this rare site of involvement among pediatric oncologists. The available evidence and expert consensus statements are summarized.

Definition of cortical bone involvement in the staging of newly diagnosed pediatric Hodgkin lymphoma: A report from the International Working Group on Staging Evaluation and Response Criteria Harmonization (SEARCH).

BACKGROUND: The International Working Group on Staging Evaluation and Response Criteria Harmonization (SEARCH) seeks to provide a universally acceptable definition of cortical bone involvement in the staging of newly diagnosed pediatric Hodgkin lymphoma. PROCEDURE: A comprehensive literature search was performed using PubMed and Google Scholar with the search terms "Hodgkin lymphoma," "osseous lesions," "bony involvement," and "pediatric." Publications reviewed included case reports, retrospective analyses, and literature reviews. Each was evaluated for study design, number of participants, median age and age range at diagnosis, percentage of pediatric patients, criteria of interest definition, diagnostic tools, study objectives, and level of evidence. The final definition was based on the available data and consensus of the SEARCH working group. RESULTS: Twenty-five papers specifically addressing cortical bone involvement in Hodgkin lymphoma met the inclusion criteria. Eighteen papers were case reports with literature reviews; the remainder were observational cohort studies. Of these, 14 included pediatric patients (aged 0-21 years). The criteria for cortical bone involvement were not clearly defined in any paper, often varied within a study, and were inconsistent between publications. CONCLUSIONS: The SEARCH group for Childhood, Adolescent, and Young Adult Hodgkin Lymphoma (CAYAHL) proposes the following criteria as defining cortical bone involvement: any cortical bone biopsy-proven lesion; a positive bony window lesion on computer tomography (CT), with an FDG-PET positive correlate in a patient with biopsy-proven Hodgkin lymphoma, if there is no other typical skeletal pathology; auspicious skeletal lesions on FDG-PET or magnetic resonance imaging should be confirmed by CT or Tc-99m scan to distinguish cortical lesions from bone marrow involvement. Nodal masses that extend into bone with bony destruction are considered extranodal extension or "E" lesions and do not represent metastatic or stage IV disease.

Imaging for diagnosis, staging and response assessment of Hodgkin lymphoma and non-Hodgkin lymphoma.

Hodgkin lymphoma and non-Hodgkin lymphoma are common malignancies in children and are now highly treatable. Imaging plays a major role in diagnosis, staging and response using conventional CT and MRI and metabolic imaging with positron emission tomography (PET)/CT and PET/MRI. Cross-sectional imaging has replaced staging laparotomy and splenectomy by demonstrating abdominal nodal groups and organ involvement. [F-18]2-fluoro-2-deoxyglucose (FDG) PET provides information on bone marrow involvement, and MRI elucidates details of cortical bone and confirmation of bone marrow involvement. The staging system for Hodgkin lymphoma is the Ann Arbor system with Cotswald modifications and is based on imaging, whereas the non-Hodgkin staging system is the St. Jude Classification by Murphy or the more recent revised International Pediatric Non-Hodgkin Lymphoma Staging System (IPNHLSS). Because all pediatric lymphomas are metabolically FDG-avid and identify all nodal, solid organ, cortical bone and bone marrow disease, staging evaluations require FDG PET as PET/CT or PET/MRI in both Hodgkin and non-Hodgkin lymphoma. Both diseases have in common issues of airway compromise at presentation demonstrated by imaging. Differences exist in that Hodgkin lymphoma has several independent poor prognostic factors seen by imaging such as large mediastinal adenopathy, Stage IV disease, systemic symptoms, pleural effusion and pericardial effusion. Non-Hodgkin lymphoma includes more organ involvement such as renal, ovary, central nervous system and skin. Early or interim PET-negative scans are a reliable indicator of improved clinical outcome and optimize risk-adapted therapy and patient management; imaging may not, however, predict who will relapse. A recent multicenter trial has concluded that it is usually sufficient for pediatric lymphoma at staging and interim assessment to evaluate children with PET imaging from skull base to mid-thigh. Various systems of assessment of presence of disease or response are used, including the Deauville visual scale, where avidity is compared to liver; Lugano, which includes size change as part of response; or quantitative PET, which uses standardized uptake values to define more accurate response. Newer methods of immunotherapy can produce challenges in FDG PET evaluation because of inflammatory changes that may not represent disease.

Response-adapted therapy for the treatment of children with newly diagnosed high risk Hodgkin lymphoma (AHOD0831): a report from the Children's Oncology Group.

The AHOD0831 study for paediatric patients with high risk Hodgkin lymphoma tested a response-based approach designed to limit cumulative alkylator exposure and reduce radiation volumes. Patients (Stage IIIB/IVB) received two cycles of ABVE-PC (doxorubicin, bleomycin, vincristine, etoposide, prednisone, cyclophosphamide). Rapid early responders [RER, no positron emission tomography (PET) activity above mediastinal blood pool] were consolidated with 2 cycles of ABVE-PC. Slow early responders (SER) received 2 cycles of ifosfamide/vinorelbine and 2 cycles of ABVE-PC. Radiotherapy was administered to sites of initial bulk and/or SER. By intent-to-treat analysis, 4-year second event-free survival (EFS; freedom from second relapse or malignancy) was 91·9% [95% confidence interval (CI): 86·1-95·3%], below the projected baseline of 95% (P = 0·038). Five-year first EFS and overall survival (OS) rates are 79·1% (95% CI: 71·5-84·8%) and 95% (95% CI: 88·8-97·8%). Eight of 11 SER patients with persistent PET positive lesions at the end of chemotherapy had clinical evidence of active disease (3 biopsy-proven, 5 with progressive disease or later relapses). Although this response-directed approach did not reach the ambitiously high pre-specified target for second EFS, EFS and OS rates are comparable with results of recent trials despite the reduction in radiotherapy volumes from historical involved fields. Persistent PET at end of chemotherapy identifies a cohort at an especially high risk for relapse/early progression.

Brentuximab vedotin with gemcitabine for paediatric and young adult patients with relapsed or refractory Hodgkin's lymphoma (AHOD1221): a Children's Oncology Group, multicentre single-arm, phase 1-2 trial.

BACKGROUND: Patients with primary refractory Hodgkin's lymphoma or early relapse have a poor prognosis. Although many salvage regimens have been developed, there is no standard of care. Brentuximab vedotin and gemcitabine have been shown to be active in patients with relapsed or refractory Hodgkin's lymphoma when used as monotherapy, and each has been successfully used in combination with other agents. Preclinical data suggest that brentuximab vedotin can sensitise lymphoma cells to gemcitabine, supporting the use of the combination. We aimed to define the safety and efficacy of brentuximab vedotin with gemcitabine in children and young adults with primary refractory Hodgkin's lymphoma or early relapse. METHODS: In this Children's Oncology Group, multicentre, single-arm, phase 1-2 trial, we recruited patients with Hodgkin's lymphoma from hospitals across the USA and Canada. Eligible patients were aged younger than 30 years, had no previous brentuximab vedotin exposure, and had primary refractory disease or relapse of less than 1 year from completion of initial treatment. Each 21-day cycle consisted of 1000 mg/m2 intravenous gemcitabine on days 1 and 8 and intravenous brentuximab vedotin on day 1 at 1·4 mg/kg or 1·8 mg/kg. The primary objectives were to establish the recommended phase 2 dose of brentuximab vedotin in this combination, the safety of the combination, and the proportion of patients who achieved a complete response among those treated at the recommended phase 2 level, within four cycles of treatment. This trial is registered with ClinicalTrials.gov, number NCT01780662. FINDINGS: Between Feb 5, 2013, and Aug 19, 2016, 46 patients were enrolled, including one who was found to be ineligible, in the two phases of the study. The recommended phase 2 dose of brentuximab vedotin was 1·8 mg/kg in combination with gemcitabine 1000 mg/m2. 24 (57%) of 42 evaluable patients (95% CI 41-72) given this dose level had a complete response within the first four cycles of treatment. Four (31%) of 13 patients with a partial response or stable disease had all target lesions with Deauville scores of 3 or less after cycle 4. By modern response criteria, these were also complete responses (total number with complete response 28 [67%] of 42 [95% CI 51-80]). The most common grade 3-4 adverse events in all 42 participants treated at the recommended phase 2 dose were neutropenia (15 [36%]), rash (15 [36%]), transaminitis (9 [21%]), and pruritus (4 [10%]). There were no treatment-related deaths. INTERPRETATION: Brentuximab vedotin with gemcitabine is a safe combination treatment with a tolerable toxicity profile for patients with primary refractory Hodgkin's lymphoma or high-risk relapse. The preliminary activity of this combination shown in this trial warrants further investigation in randomised controlled trials. FUNDING: National Institutes of Health and the St. Baldrick's Foundation.