Melatonin May Prevent Breast Cancer Development

PARIS--Melatonin appears to have both preventive and curative effects on mammary carcinogenesis, according to research published in Breast Cancer Research (7, 4:470-476, 2005) (http://breast-cancer-research.com/content/7/4/R470/abstract).

The results of the study showed almost identical preventive and curative effects of melatonin on the growth of dimethylbenz [a]anthracene-induced (DMBA-induced) mammary adenocarcinoma (ADK). This study sought to determine the necessary potency for melatonin to have a curative effect and the potency required to limit the frequency of mammary cancer initiation. The researchers found 10 mg/d of melatonin in female rats 15 days before administration of DMBA had the same effect on DMBA-induced mammary ADK as the long-term (six-month) curative treatment with the same dose of melatonin starting the day after DMBA administration. The rats were followed up for a year after the administration of DMBA.

Several theories were proposed to explain the inhibitory mechanisms of melatonin, but its preventive mechanisms are still unclear. However, the study concluded melatonin's artificial amplification of the intensity of the circadian rhythm could markedly reduce DNA damage provoked by DMBA and therefore limit the frequency of cancer initiation. Long-term inhibition of mammary ADK promotion may be achieved by a brief, preventive treatment with melatonin, reducing the risk of breast cancer in women due to unidentified environmental factors.