CD4 and neoplasm: While in non-obstructive T4 tumors, the densities of various immune cells (CD4+ T, CD8+ T, CD20+ B cells) in the IM remain positively correlated with peripheral blood lymphocyte counts (indicating preserved communication between local and systemic immunity), in obstructive T4 tumors, all correlations between tumor-infiltrating immune cell subsets (both in IM and CT) and peripheral blood immune parameters are completely absent.