Maebayashi T, et al. - Between 1999 and 2016, authors assessed 13 cases to evaluate the relationships of Ki-67 proliferation index and p16 expression status with treatment outcomes of subjects with unknown primary head and neck squamous cell carcinoma (SCC). They observed the 2- and 5-year overall survival (OS) rate, 76.9%, and 68.4%, respectively for Ki-67 proliferation index and p16 expression status. They found no significant variation in survival between subjects with a high Ki-67 vs low Ki-67 or between cases with p16-positive vs p16-negative metastases OS. They concluded that the combination of ki67 expression and p16 expression status could predict local control more precisely as compared to p16 expression status alone.