Management of Squamous Cancer Metastatic to Cervical Nodes With an Unknown Primary Site.

Squamous cell carcinoma of an unknown primary (SCCUP) of the head and neck is a rare disease. As a diagnosis of exclusion, the manner in which it is assigned merits consideration. Despite the development and refinement of several techniques designed to locate an occult tumor, including cross-sectional anatomic imaging, functional imaging, and transoral surgical techniques, delineating SCCUP remains an active clinical problem. Its relative rarity has prevented prospective study of the entity. Hence, investigators must rely on retrospective analyses to understand the disease and its appropriate treatment. The current understanding of SCCUP differs substantially from when it was initially described decades ago. The most common site of a small primary tumor initially thought to represent SCCUP is the tonsil or base of the tongue, and an increasing percentage are associated with human papilloma virus. Modern treatment of SCCUP by neck dissection alone, neck dissection followed by radiation with or without concurrent chemotherapy, or primary chemoradiation according to initial nodal disease burden produces extraordinarily low recurrence rates. Whether the potential mucosal primary site and/or the contralateral neck should be electively treated is controversial. Efficacy data seem to be similar; therefore, an evaluation of the toxicity of both treatment paradigms is warranted.