Results of an Ontario Clinical Oncology Group (OCOG) prospective cohort study on the use of FDG PET/CT to predict the need for neck dissection following radiation therapy of head and neck cancer (HNC).

5504 Background: A significant proportion of node-positive HNC patients will have residual nodes visible on CT following curative radiation therapy +/- concurrent chemotherapy (RT+/-Chemo). A third of these will harbor residual cancer and can be cured by neck dissection (ND). This study examines the ability of PET/CT to detect residual nodal cancer following RT+/-Chemo in HNC patients. Methods: This prospective multi-center study was conducted at 4 regional cancer centers in Ontario. Eligible patients had squamous cell carcinomas with N2 or N3 neck disease. They were treated curatively with RT+/-Chemo to include full radiation dose to nodes deemed involved by tumor. Contrast enhanced CT scans and PET/CT were performed prior to and 8-10 weeks following RT+/-Chemo. Patients with residual nodes >1cm axial dimension on CT were mandated to undergo ND within 4 weeks of imaging. The pathologic results of ND were correlated with post treatment imaging. Patients were followed for neck recurrence for 2 years. Resul...