CD4 and lung cancer: We collected laboratory test indicators in 45 patients with HIV-related lung cancer, which included CD4 + T cell count, CD8 + T cell count, CD4 + T/CD8 + T cell count, carcinoembryonic antigen (CEA), CA125, pro-gastrin releasing peptide (ProGRP), neuron-specific enolase (NSE), squamous cell carcinoma antigen (SCC), and cytokeratin 19 fragment (CYFRA21-1).