Autonomic nervous system and cancer.

The autonomic nervous system (ANS) is the main homeostatic regulatory system of the body. However, this widely distributed neural network can be easily affected by cancer and by the adverse events induced by cancer treatments. In this review, we have classified the ANS complications of cancer into two categories. The first includes direct cancer-related complications, such as primary ANS tumors (pheochromocytoma, paraganglioma or neuroblastoma), as well as autonomic manifestations induced by non-primary ANS tumors (primary brain tumors and metastases). The second comprises indirect ANS complications, which include autonomic features related to cancer therapy (chemotherapy, radiotherapy and/or surgery) and those not related to cancer therapy, such as paraneoplastic autonomic syndromes. We also review the molecular relationship and modulation between the ANS and the cancer cells and their microenvironment.