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 (MR_CXR) > 1/3; (ii) mediastinal mass ratio on CT (MR_CT) > 1/3; (iii) mediastinal mass volume on CT (MV_CT) > 200 mL; (iv) normalized mediastinal mass volume (MV_CT/thoracic diameter [TD]) > 1 mL/mm; (v) mediastinal mass diameter on CT (MD_CT) > 10 cm; and (vi) normalized mediastinal mass diameter (MD_CT/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, MV_CT > 200 mL, MD_CT > 10 cm, and MD_CT/TD > 1/3 were associated with worse relapse-free survival (RFS) on MVA, while MR_CXR > 1/3, MR_CT > 1/3, and MV_CT/TD > 1 mL/mm trended toward worse RFS; MD_CT/TD was the most strongly prognostic for inferior RFS, with a hazard ratio of 6.41 for MD_CT/TD > 1/3 versus ≤1/3 on MVA (p =.02). Conclusion: LMA according to MV_CT > 200 mL, MD_CT > 10 cm, and MD_CT/TD > 1/3 is associated with poor prognosis in advanced-stage HL patients with SER. The normalized mediastinal diameter, MD_CT/TD > 1/3 appears to be the strongest predictor of inferior RFS.