Cancer of unknown primary in the head and neck: Diagnosis and treatment.

Cancer of unknown primary in the head and neck is defined by the presence of cancer in one or more lymph nodes within the head and neck region, not confined to the supraclavicular region, without an identifiable primary tumor. These primary sites are increasingly being identified with the help of advanced diagnostic techniques such as endoscopy, PET/CT, the HPV test, the EBV test, evaluation of biomarkers, and pathological examination. However, the remainder of these patients fall into the category of metastatic cervical cancer of unknown primary (MCCUP). MCCUP accounts for approximately 3-5% of all head and neck squamous cell carcinomas (HNSCCs). Moreover, optimal therapy for patients with MCCUP is still controversial. The treatment options range from neck dissection alone to irradiation of the bilateral neck, with or without irradiation of plausible primary sites as well. In future, precision medicine should improve the diagnosis and methods of therapy for MCCUP patients.