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.
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