Patients with esophageal and gastric cancer show a decreased diurnal excretion of DOPA matched by a considerable drop in the urine levels of catecholamines and their main metabolites as compared with healthy subjects. This points to a severe inhibition of synthesis and metabolism of catecholamines at all stages. Tumor process progression is accompanied by an ever-increasing inhibition of sympatho-adrenal system function. Simultaneously, disorders develop in the functioning of the cholinergic structures of the nervous system.