[Investigation for cervical lymph node metastasis in unknown primary sites]

In patients with cervical adenopathy, especially, those of cervical lymph node metastasis with no detectable primary tumor, diagnosis and treatment planning can become confused. We evaluated 36 patients with cervical lymph node metastasis of unknown origin between 1985 and 2002. Primary sites were detected in 20 before treatment. The other 36 patients clearly had no primary lesions when treatment started. Primary sites were 5 cases of oropharynx, 2 of the parotid gland, and 1 each of larynx, nasopharynx, hypopharynx, and malignant lymphoma detected in 11 after treatment for cervical lymph nodes. No primary lesion was found in 28 patients. The neck LN stage was N1 in 11 patients, N2 in 29, N3 in 11, and unknown in 8. To detect the primary site, we conducted "random" biopsy, panendoscopy, and radiographic evaluation including FDG-PET. Biopsy sites were the nasopharynx, palatine and lingual tonsil, and piriform sinus. Some 35 patients (59.3%) underwent random biopsy, and primary sites were found this way in 5 patients (14.3%). The 36 who had no primary lesion were treated for cervical lymph nodes, of whom 24 underwent neck dissection. Chemotherapy and radiotherapy were the treatment of choice in many cases. We analyzed 31 patients for 5 year survival. Overall survival was 63.7%, disease-specific survival 69.2%, and disease-free survival 46.8%. In another analysis a statistically significant difference was seen in survival among patients who had neck surgery or not (85.7% vs. 38.9%, p = 0.029; log rank test). Analysis suggested that primary sites should be studied by CT, MRI, FDG-PET, and panendoscopy, including random biopsy. The primary site cannot be detected, treatment should initially involve cervical adenopathy with combined surgery, chemotherapy, and radiotherapy. After treatment, the patient should be followed up carefully to find the primary lesion.