Participants and Setting
We included all patients diagnosed and treated at CHEO between January 1994 and December 2014 for a diagnosis of Hodgkin Lymphoma (HL), Wilms Tumour (WT) or extracranial germ cell tumour (GCT). WT and GCT are two types of embryonal tumours. CHEO is a tertiary care pediatric hospital in Ottawa, Canada with a medium-sized pediatric oncology program, treating approximately 70 new oncology patients per year. Included patients were <18 years at diagnosis and received both pulmonary function testing and pulmonary toxic treatment. We limited inclusion to children with a minimum of two acceptable pulmonary function tests (PFT), with at least one test performed within 90 days following treatment completion and prior to any relapse, in order to capture the onset of pulmonary function changes related to initial treatment. Our centre only performs pulmonary function testing on children 6 and older, so children below this age cut-off were excluded.