Diagnosis and management of neck metastases from an unknown primary

Neck lymph node metastases from occult primary constitute about 5%-10% of all patients with carcinoma of unknown primary site. Metastases in the upper and middle neck (levels I-II-III-V) are generally attributed to head and neck cancers, whereas the lower neck (level IV) involvement is often associated with primaries below the clavicles. Diagnostic procedures include a careful clinical evaluation and a fiberoptic endoscopic examination of the head and neck mucosa, biopsies from all suspicious sites or blindly from the sites of possible origin of the primary, computerized tomography scan, and magnetic resonance. The most frequent histological finding is Squamous Cell Carcinoma, particularly when the upper neck is involved. In these cases, a systematic tonsillectomy in the absence of suspicious lesions is discussed since up to 25% of primary tumours can be detected in this site. Thoracic, and abdominal primaries (especially from lung, oesophagus, stomach, ovary or pancreas) should be sought in the case of adenocarcinoma and involvement of the lower neck. Positron emission tomography with fluoro-2-deoxy-D-glucose allows detection of primary tumour in about 25% of cases, but this procedure is still considered investigational. Therapeutic approaches include surgery (neck dissection), with or without post-operative radiotherapy, radiotherapy alone and radiotherapy followed by surgery as reported by several guide-lines. In early stages (N1), neck dissection and radiotherapy seem to have similar efficacy, whereas more advanced cases (N2, N3) require combined approaches. The extent of radiotherapy (irradiation of bilateral neck and mucosa versus ipsilateral neck radiotherapy) remains debatable. A potential benefit from extensive radiotherapy should be weighed against its acute and late morbidity and difficulties in re-irradiation in the case of subsequent primary emergence. The role of other methods, such as chemotherapy and hyperthermia, remains to be determined.