Lee, Inki

Purpose In lymphomas, the Deauville score (DS) standardizes 18F-FDG PET treatment response assessments. We assessed interobserver agreement of the DS and developed a quantitative PET-based parameter to minimize subjectivity of response assessments. Methods PET scans performed within the Children’s Oncology Group AHOD0831 study were analyzed. One hundred one scans obtained after the first cycle of chemotherapy (PET1) and 83 obtained after the second cycle (PET2) were eligible for inclusion. Each scan was assigned a DS by 2 nuclear medicine radiologists and a Hodgkin lymphoma index (HLI), defined as the ratio of the tumor’s SUVmax or SUVpeak to the liver’s SUVmean. Cohen κ coefficient measured the rate of agreement of the DS assigned by the 2 radiologists. Receiver operating characteristic curves and the Youden index were used with the consensus DS to identify an optimal HLI cutoff value to distinguish PET-negative from PET-positive images. For each HLI cutoff value, sensitivity, specificity, and accuracy were calculated. Results Interobserver agreement in DS was moderate (PET1: κ = 0.480, P < 0.001; PET2: κ = 0.428, P < 0.001). On PET1, the optimal cutoff values for HLImax were 1.19 for DS2/DS3 and 1.78 for DS3/DS4, and for HLIpeak were 1.19 for DS2/DS3 and 1.44 for DS3/DS4. On PET2 images, the corresponding values were 1.18, 1.58, 0.94, and 1.26. The most accurate predictor was HLImax on PET2 when scans were dichotomized as DS1–DS3 versus DS4–DS5 (accuracy, 92.8%; sensitivity, 100%; specificity, 91.8%). Conclusion The HLI provides an objective, quantitative measure of disease response and thus may improve interreader agreement for lymphoma response assessments.

AbstractPurpose/objectiveWe 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/methodsTotal 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.ResultsMedian 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).ConclusionLMA 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.

SummaryThe 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.