Incidence and sites of distant metastases from head and neck cancer

The incidence of distant metastases in head and neck squamous cell carcinom a (SCC) is relatively small in comparison to other malignancies. Distant me tastases adversely impact survival and may significantly affect treatment p lanning. The incidence of distant metastases is influenced by location of t he primary tumor, initial T and N stage of the neoplasm, and the presence o r absence of regional control above the clavicle. Patients with advanced no dal disease have a high incidence of distant metastases, particularly in th e presence of jugular vein invasion or extensive soft tissue disease in the neck. Primary tumors of advanced T stages in the hypopharynx, oropharynx a nd oral cavity are associated with the highest incidence of distant metasta ses. Pulmonary metastases are the most frequent in SCC, accounting for 66% of distant metastases. It may be difficult to distinguish pulmonary metasta sis from a new primary tumor, particularly if solitary. Other metastatic si tes include bone (22%), liver (10%), skin, mediastinum and bone marrow. An important question remains as to how intensely pre- and postoperative scree ning for distant metastases should be performed. Preoperative chest Xray is warranted in all cases. If the primary tumor and nodal status place the pa tient at high risk for pulmonary metastasis, then preoperative computed tom ography scan of the chest should be done. Screening for distant metastases at other sites is usually not indicated in SCC of the upper aerodigestive t ract. Postoperatively, annual X-rays of the chest are usually sufficient, b ut in high-risk situations a chest X-ray performed every 3-6 months may be beneficial. Certain histologic types of primary tumor have greater or lesse r propensity to metastasize distantly, and have a different natural history . Adenoid cystic carcinoma metastasizes frequently, even in the absence of extensive local or regional disease. Basaloid squamous cell carcinoma and n euroendocrine carcinomas also metastasize widely. Extensive evaluation for distant metastases is justified for these tumors. Knowledge of the natural history of various neoplasms and the factors that contribute to distant met astases as well as good judgement are essential for cost-effective treatmen t planning and decision-making with regard to pre- and postoperative evalua tion for distant metastases in cancer of the head and neck. Copyright (C) 2 001 S.Karger AG, Basel.