Dynamics of circadian fluctuations in serum concentration of cortisol and TNF-alpha soluble receptors in gastrointestinal cancer patients.

The objective of the study was to investigate the dynamic changes of cortisol and soluble TNF-alpha p-55 and p-75 receptors in serum of advanced cancer patients during 24 h. The examined group consisted of 42 patients suffering from advanced gastrointestinal neoplasms (colorectal, gastric and pancreatic cancer). Serum levels of cortisol, TNF-alpha and both receptors in cancer patients were measured using ELISA type kits 6 times a day (8.00 a.m., 2.00 p.m., 6.00 p.m., 10.00 p.m., 2.00 a.m. and again 8.00 a.m.) as well as in healthy controls. The levels of cortisol, TNF-alpha and its soluble receptors were substantially increased in examined group and displayed statistically significant circadian fluctuations. Cortisol peak was found typically at 8.08 a.m., the minimum value appeared at 6 p.m. The presence of circadian rhythm of the cytokine was proved (acrophase -00.36 a.m.), however no diurnal rhythm of soluble TNF receptors was observed. The concentration of p-55 receptor was distinctly lower then p-75. The peak p-55 value appeared at 10.00 p. m. while the p-75 reached its minimum level at the same time. Although there was no statistical correlation between the receptor concentrations the shapes of both curves remained in inversely proportional manner to each other. The present results may suggest the presence of complex self-regulation mechanisms in advanced gastrointestinal cancer patients. There was no correlation observed between cortisol and TNF-alpha soluble receptor concentration.