CD8A and cancer: CD8 is predominantly expressed on cytotoxic T cells (CTLs) that play central roles in cell-mediated immune attack, whereas it can be expressed on natural killer and dendritic cells.15–17 Accordingly, CD8 is generally recognised as a marker of CTLs. A number of clinical studies revealed that a higher density of CD8 + TILs was associated with a favourable prognosis in a variety of malignant tumours including NSCLC,17–22 The present study also showed that a higher stromal CD8 + TIL density after cCRT was associated with a favourable prognosis (Figs. 3–5).