PDCD1 and neoplasm: High TIGIT expression was significantly associated with age (p=0.010), histological grade (p=0.014), non-lobular histology (p=0.024), adjuvant chemotherapy (p=0.006), and various immune cell populations (tumor infiltrating lymphocytes (TILs), CD3+, CD8+, PD-1+ cells; all p<0.0001), PD-L1+ tumor cells (p<0.0001), and PD-L1+ stromal cells (p=0.003).