Research is being conducted on the relationship between programmed death-ligand 1 (PD-L1) expression and overall survival in patients with gastric cancer, specifically in a thai patient population. The study of PD-L1 expression is also being explored in other types of cancer, including gastric, oral, and cervical cancer. The investigation of PD-L1 and other immune-related factors is a broader area of research, with potential implications for cancer treatment and prognosis.