RATHL is a multicentre, randomised, phase III trial comparing treatment outcome for patients with advanced Hodgkin lymphoma, using FDG-PET imaging after 2 cycles of ABVD to determine response and subsequent management. Recruitment target: 1200 patients Patients received 2 cycles of ABVD and then had a PET-CT scan. PET negative patients were randomised to either ABVD or AVD for a further 4 cycles. PET positive patients received either BEACOPP-14, for 4-6 cycles or BEACOPP escalated, for 3-4 cycles. Samples collected for trial: Formalin fixed paraffin embedded tumour block - sent to HMDS, Leeds. Blood sample to be analysed at site. Blood sample - sent to Simpson Centre for Reproductive Health, Edinburgh.