How do you define bulky mediastinal disease in Hodgkin's lymphoma?

Bulk in HL (outside the mediastinum) has been defined variably. While Children's Oncology Group studies used a threshold of 6 cm recently, the European studies and medical oncology trials have often used 10 cm as the threshold.

On the recently accrued AHOD1331 COG trial, bulk was defined as a contig...