Roles of Ki-67 and p16 as biomarkers for unknown primary head and neck squamous cell carcinoma

Purpose Treatment guidelines have not been established for unknown primary head and neck squamous cell carcinoma (SCC). For these patients, chemoradiotherapy (CRT) can provide a better prognosis than that for patients with other head and neck cancers. The presence of HPV in the tumor is associated with a better outcome. However, not all patients with HPV-positive unknown primary head and neck SCC experience good treatment outcomes in actual clinical settings.