The potential biological mechanism may be related to that tumor cells stimulate macrophages to secrete a large number of inflammatory factor such as interleukin-10 (IL-10) and tumor necrosis factor-α (TNF-α) and further to promote the expression of programmed cell death ligand 1 (PD-L1) and eventually make cancer cells escape from the attack of T cells [31]. This evidence concerns the gene TNF and cancer.