Metastatic head and neck cancer: Role and usefulness of FDG PET in locating occult primary tumors

PURPOSE: To assess the usefulness of 2-[fluorine-18]fluoro-2-deoxy-D-glucos e (FDG) positron emission tomography (PET) of the head and neck in locating occult primary lesions in patients with metastatic cervical adenopathy. MATERIALS AND METHODS: Seventeen patients with metastatic cervical adenopat hy of unknown primary origin were referred for FDG PET of the head and neck . All patients had undergone correlative anatomic imaging within 1 month of FDG PET. Surgical, clinical, and histopathologic findings were used to ass ess the performance of FDG PET. RESULTS: Increased apical lung uptake at FDG PET led to a biopsy-proved dia gnosis of primary lung cancer in two patients. Of the remaining 15 patients , 10 had a focus of increased activity; directed biopsy of these sites led to confirmation of a primary carcinoma in seven patients. Correlative anato mic imaging failed to demonstrate the primary sites of disease in two of th ese seven patients. None of the five patients with negative FDG PET studies have manifested evidence of a primary site of disease during follow-up of 8-42 months (mean, 29 months). CONCLUSION: FDG PET allows effective localization of the unknown primary si te of origin in metastatic heed and neck cancer and can contribute substant ially to patient care.