DiagnosticsO-001. Role and usefulness of FDG-PET in patients with metastatic cervical lymph nodes from an Unknown Primary Tumor

Aims: Patients presenting with a cervical lymph node metastasis of an unknown primary tumor are subject to thorough investigations including clinical examination, imaging techniques and panendoscopy. Positron Emission Tomography (PET) is a technique that visualizes metabolic changes and may be of use in detecting the primary tumor or other metastases. The purpose of this study was to evaluate the value of PET in detecting a primary tumor or distant metastases in patients suffering from cervical lymph node metastases from an unknown primary tumor. Method: Forty-four patients, with cytological proven cervical lymph node metastases from clinically unknown primary tumors, were studied retrospectively. All patients underwent an FDG-PET whole body scan, panendoscopy and imaging (CT and/or MR). Results: FDG-PET showed hot spots, indicative for a primary tumor or extended metastases, in 36% of all patients. FDG-PET failed to detect two primary tumors found by panendoscopy, while one primary tumor was detected with FDG-PET only. Both sensitivity and specificity of FDG-PET for detecting primary tumors and distant metastases in this study was 88%. Conclusion: Taking FDG-PETs major drawback, 5% false negative results, into account, this method proved to be a valuable tool in detecting primary tumors and distant metastases in patients suffering from cervical metastases from an unknown primary tumor. Further research should be performed, preferably in a prospective protocol.