2(F-18)-fluoro-2-deoxy-D-glucose positron emission tomography is a sensitive tool for the detection of occult primary cancer (carcinoma of unknown primary syndrome) with head and neck lymph node manifestation

BACKGROUND: The neck lymph nodes are a common site of metastases from carci noma of unknown primary (CUP syndrome). 2(F-18)-fluoro-2-deoxy-D-glucose po sitron emission tomography (18-FDG-PET) has been shown to be a sensitive to ol for detecting primary malignant lesions as well as metastatic spread. We have prospectively investigated the sensitivity of 18-FDG-PET in detecting occult primary carcinomas with manifestation in the head and neck lymph no des. METHODS: From May 1994 to July 1998, in 723 patients a cancer of the head a nd neck was diagnosed at the University of Cologne ENT outpatient clinic. T he routinely performed staging procedures were chest radiography; full bloo d count; cervical and liver ultrasound; endoscopy of the nasopharynx, oroph arynx, hypopharynx, larynx, and esophagus; and laboratory analyses. After t he staging workup, in 27 of 723 patients (3.7%) CUP syndrome had to be pres umed because the primary cancer could not be detected. In these patients 18 -FDG-PET was performed, and images were reconstructed with a transmission-e mission fusion technique. RESULTS: In 7 of 27 patients (26%) 18-FDG-PET revealed an unknown primary: in 2 a bronchial carcinoma, in 2 a nasopharyngeal carcinoma, in 1 a squamou s cell carcinoma of the parotid gland, in 1 a squamous cell carcinoma of th e hypopharynx, and in 1 a carcinoma of the tonsil. In 4 of 7 patients the o ccult primary tumor was removed surgically. In 8 of 27 patients therapeutic strategy was changed as a result of the 18-FDG-PET findings. CONCLUSION: 18-FDG-PET should be performed in all patients with CUP syndrom e after conventional diagnostic workup fails to identify the primary.