[Melatonin for diagnosis of cancer and assessment of prognosis in elderly patients].

A review is given on the analysis of melatonin (MT) and of its main peripheral metabolite 6-sulfatoxymelatonin (aMT6s) in old patients with different types of primary unoperated carcinomas. A very low production of melatonin (as estimated by the nocturnal urinary excretion of aMT6s) was found in male patients with lung or stomach cancer compared to aged-matched controls as well as in female patients with thyroid cancer. The levels of these women, however, did not differ from female patients with benign thyroid diseases indicating a general suppressive effect of thyroid diseases on the pineal gland. A similar but opposite phenomenon was observed in male patients with primary unoperatide colorectal cancer which showed an elevated production of mellatonin when compared to healthy men but not when compared to patients with colitis ulcerosa. The mechanisms involved in these phenomena are poorly understood and seem to include central as well as peripheral components. This view is supported by the finding that in spite of varying urinary aMT6s excretion measured in patients with different types of tumor, aMT6s shows comparable positive correlations with the degree of tumor cell proliferation (as estimated by the number of PCNA-immunopositive cells). Therefore the amount of aMT6s excreted (as well as the corresponding concentration of circulating MT) has to be understood as the net result of a number of different effects by the tumor on organism.