CD274 and Epstein-Barr virus infection: The PD-L1 positivity in nasopharyngeal cancer is common especially for those with EBV infection or WHO type 3 undifferentiated carcinoma histology.[13] The high expression of PD-L1 in nasopharyngeal cancer has been shown in some studies to confer favorable prognosis to overall survival or progression free survival.[12,15] Nevertheless, there were also multiple studies shown that PD-L1 expression was not prognostic[12,13] or even conferred negative prognosis[16–19] in nasopharyngeal cancer.