Fig. 2.

Schematic showing how parasympathetic nervous system activation reduces tumor growth and metastasis via decreased expression of PD-1 and PD-L1 while increasing release of IFN-γ from CD4⁺ and CD8⁺ tumor-infiltrating lymphocytes. As shown, denervation of the parasympathetic system or vagotomy decreases gastric tumorigenesis through Wnt signaling and causes a similar outcome in colorectal cancer cases. Increased cytokines, TNF-α, and TAMs; high invasiveness; and decreased survival rates are the results of vagotomy in patients with other cancers such as prostate, pancreatic, and breast cancer. The figure was created with BioRender.com.