Neuro-Endocrine-Immune Network Comprehensively Modulates the Tumor Process

The nervous, endocrine, and immune systems represent three basic regulatory systems that interact with each other in a bidirectional manner to form a neuro-endocrine-immune regulatory network (Fig. 6.1). This network allows the activity of all cells of the organism to be adequately regulated. The integration of endocrine and immune functions under the control of the nervous system has several advantages for the organism. The brain ensures the integration and synchronization of the basic regulatory systems, which is essential for the maintenance of homeostasis or allostasis, and, if tissue damage occurs, allows the appropriate activation of repair and regenerative responses. Another factor is the prediction of when the brain initiates compensatory/adaptive responses before homeostasis is disturbed, thus preventing unnecessary allostatic overload of the organs and tissues involved. Finally, it is a matter of speed, whereby the brain can react promptly via neural pathways to unfavorable factors operating in the external or internal environment and thus prevent more severe fluctuations in homeostasis (Verburg-van Kemenade et al. 2017; Schiller et al. 2021).