CD8A and head and neck squamous cell carcinoma: In contrast to the T helper cells, non-recurrent SCCHN patients had significantly higher proportions of cytotoxic CD8+ T cells at all time points (t0, t1, t2, t3) compared to controls (Ctrl vs. t0: 10.83% vs. 17.12%, Ctrl vs. t1: 10.83% vs. 19.03%, Ctrl vs. t2; 10.83% vs. 25.44%, Ctrl vs. t3: 10.83% vs. 10.54%, p ≤ 0.001; Fig. 1d, Additional file 1: Table S2).