Depression of serum melatonin in patients with primary breast cancer is not due to an increased peripheral metabolism.
Serum melatonin and its main metabolic product 6-sulfatoxymelatonin were determined in 17 patients with breast cancer (BC) with either a fresh primary tumor (nine) or a secondary tumor (eight) as well as in four patients with untreated benign breast disease (controls). Circadian rhythms were detected in all groups with acrophases around 2 AM for melatonin and around 3 AM for 6-sulfatoxymelatonin. The nocturnal melatonin and 6-sulfatoxymelatonin concentrations were significantly depressed in the group of patients with primary breast cancer compared with controls (P less than 0.01, P less than 0.025). The circadian amplitudes of melatonin and 6-sulfatoxymelatonin were also depressed by 81% (P less than 0.01) and 63% (P less than 0.01). In contrast, patients with secondary BC had nocturnal melatonin and 6-sulfatoxymelatonin concentrations and amplitudes similar to controls. These results demonstrate that the depression of circulating melatonin in patients with primary BC is not due to an enhanced degradation to 6-sulfatoxymelatonin in the liver but must be due to a reduced activity of the pineal gland.
Bartsch
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Department of Gynecology, University of Tübingen, Germany.
Bartsch
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Bellmann
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Lippert
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TH
D000328:Adult; D001943:Breast Neoplasms / Q000378:metabolism*; D002940:Circadian Rhythm / Q000502:physiology; D005260:Female; D006801:Humans; D008550:Melatonin / Q000031:analogs & derivatives / Q000097:blood*; D008875:Middle Aged
C054513:6-sulfatoxymelatonin; D008550:Melatonin