Additionally, the ratios of CD8+/CD4+ regulatory T cells displayed a significant negative correlation with ITH scores by MATH, PhyloWGS, ABSOLUTE, DEPTH, and tITH in 9, 9, 6, 21, and 21 cancer types, respectively, compared to DEPTH2 in 18 cancer types (P < 0.05) (Fig. 9C). Here, CD8A is linked to cancer.