CD4 and head and neck squamous cell carcinoma: This is in accordance with the systematic review and meta-analysis on the prognostic role of TILs in HNSCC by de Ruiter et al., who reported that in HPV-negative cohorts high CD4-positive TIL numbers were associated with a better OS and locoregional control [13] Though it contradicts with another meta-analysis, in which CD4-positive TILs were reported to be associated with a lower risk of death in OPSCC, but not in OSCC [33] Moreover, both studies reported on the favorable survival associated with high concentrations of CD8-positive TILs, which was not found in our study.