CD8A and digestive system cancer: DCLK1 expression level in colon tumor tissues was positively correlated with infiltrating CD8+ T cells (r = 0.28, p < 0.0001), M2 macrophages (r = 0.45, p < 0.0001), Treg (r = 0.45, p < 0.0001) (Figure 3C–E), B cells (r = 0.42, p < 0.0001), and M1 macrophages (r = 0.24, p < 0.0001) (Figure S5A,D) in COAD.