HNCUP update: Current perspectives and proven approaches in head and neck cancer of unknown primary

Introduction Head and neck carcinomas of unknown primary (HNCUP) pose a diagnostic challenge, as no primary tumor can be found in 2-5% of patients with head and neck tumors and cervical lymph node metastases. Squamous cell carcinomas are the most common histology at 53-77%. The 5-year survival rates vary considerably from 29% to 82%.