CD8A and breast cancer: Although various studies have examined the overexpression of different immune checkpoints on T cells and their links to T cell exhaustion in cancers such as colorectal cancer, melanoma, NSCLC, breast cancer, liver cancer, and other tumors, our analysis represents, to the best of our knowledge, the most comprehensive assessment of the co-expression patterns of CD8+ T cell immune checkpoint markers and their impact on immunotherapy efficacy in patients with lung adenocarcinoma.7