The clinical significance of melatonin serum determination in oncological patients and its correlations with GH and PRL blood levels

Pineal Gland and Tumor Cell Kinetics: Serum Levels of Melatonin in Relation to Ki-67 Labeling Rate in Breast Cancer

“…In agreement with the results previously reported by other authors [14] and by ourselves [9], high blood levels of melatonin can often be observed in breast cancer women. Moreover, this study shows that breast cancer patients with positive ki-67 labeling rate tend to present lower blood levels of the pineal hormone, melatonin, in respect to the negative ones.…”

Growth inhibitory and cytotoxic effects of melatonin and its metabolites on human tumour cell lines in vitro

“…Similarly, Meyskens & Salmon (1981), when describing the in vitro response of clonogenic melanoma cells from patients to melatonin, reported stimulation of colony formation in two of 11 cases, no effect in samples from three patients and a decrease in total cloning efficiency with increasing concentrations of melatonin in the remaining six cases. This activity of melatonin has been variously ascribed to a direct cell killing effect on the cancer cells, an inhibitory effect on pituitary hormones involved in mammary cancer, a regulation of polyamine synthesis or pteridine metabolism or an immunomodulatory role (Ebels, 1980;Fraschini et al, 1980;Lissoni et al, 1987). Although melatonin undoubtedly has an influence on tumour development, interest in its bioactivity has, until recently, centred almost entirely on its effects on reproduction.…”

Seasonal changes in serum melatonin in women with previous breast cancer

“…Other researchers have noted differences in total melatonin secretion between women with breast cancer and controls (Bartsch et al, 1981(Bartsch et al, , 1989 (Lissoni et al, 1987). In the present study it is uncertain how many women may have had early metastatic disease at the time of study (30% had been node positive at initial surgery), but all were free of clinically apparent breast cancer.…”

“…Ovarian oestrogen production in seasonally breeding mammals is regulated in part by the pineal hormone melatonin (Arendt, 1988), and there is evidence for seasonal variation in melatonin secretion and ovarian steroidogenesis in humans (Kauppila et al, 1987). Serum melatonin levels in women with breast cancer appear to differ from controls (Blask, 1984;Lissoni et al, 1987) and these changes are particularly apparent in relation to tumour stage (Bartsch et al, 1989) and steroid hormone receptor status (Tamarkin et al, 1982). It is uncertain whether such changes in serum melatonin have any influence on the growth of human breast cancer either directly or indirectly through ovarian oestrogen synthesis.…”