- At the time of resection a complete mediastinal lymph node resection or at least lymph node sampling should have been attempted; if a complete mediastinal lymph node resection or lymph node sampling was not undertaken, any mediastinal lymph node which measured 1.5 cm or more on the pre-surgical computed tomography (CT)/magnetic resonance imaging (MRI) scan or any area of increased uptake in the mediastinum on a pre-surgical positron emission tomography (PET) scan must have been biopsied; note: a pre-surgical PET scan is not mandatory