e17502 Background: To evaluate the diagnostic accuracy of positron emission tomography (PET) and PET/computed tomography (CT) for detecting residual and/or recurrent local and regional disease in patients with head and neck cancer (HNC) following radiotherapy with or without chemotherapy. Methods: Studies about 18FDG-PET/CT for detecting residual or recurrent disease after treatment in patients with HNC were systematically searched in the MEDLINE and EMBASE databases. The Stata software was used to obtain pooled estimates of sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio for 18FDG-PET/CT. Results: 31 articles bulled all inclusion criteria. The pooled sensitivity and specificity of PET and PET/CT for detecting residual or recurrent disease at the primary site was 88.7% and 89.6%, respectively. For residual or recurrent neck disease, the sensitivity and specificity were 75.9% and 92.0%, while for residual or recurrent localregional disease, the values were 89.6% and 87.8%. Conclusions: 18FDG-PET/CT has good diagnostic performance for the detection of residual and/or recurrent in HNC patients.