We investigated the usefulness of FDG-PET for early detection of recurrent advanced head and neck cancer after intra-arterial chemotherapy combined with radiotherapy. We examined 56 lesions (43 cases) suspected of recurrence after the chemoradiotherapy. In all cases, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of FDG-PET were 91%, 85%, 80%, 94%, and 88%, respectively. CT/MRI showed sensitivity of 88%, but poor specificity of 33% due to many false positive lesions. The specificity, accuracy, and positive predictive value of FDG-PET (85%, 88%, 80%, respectively) were significantly (p<0.05) higher than those of MRI/CT (32%, 48%, 41%). In one to two months after the combined therapy, the sensitivity, specificity, PPV, NPV, and accuracy of FDG-PET were 50%, 67%, 50%, 67%, and 60%, respectively. Between two and three months after the therapy, the sensitivity, specificity, PPV, NPV, and accuracy of FDG-PET were 100%, 93%, 89%, 100%, and 96%, respectively. FDG-PET was a better modality for the detection of recurrence after the chemoradiotherapy for advanced head and neck cancer. Two to three months after the therapy is thought to be the best timing of FDG-PET for early detection of relapse.
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