Melatonin not linked to breast cancer
against the development of breast cancer, appear to have no
relationship with risk for the cancer in humans, reports a UK team,
failing to confirm previous results from human studies.
However, they note that other prospective studies are needed to further explore the relationship.
Breast cancer is the most common cancer among women in the European Union. Each year some 60,000 women in the European Union die of it and 150,000 new cases are reported. Approximately one woman in 10 in Europe will develop breast cancer at some point in her life, according to the European Parliament's Directorate-General for Research.
Specialists at this week's European breast cancer congress in Hamburg are discussing a strategy to reduce breast cancer mortality in Europe, significantly higher than in the US.
For the melatonin study, Ruth Travis, of the British cancer charity Cancer Research UK, and colleagues compared levels of a metabolite of melatonin in the urine of 127 patients diagnosed with breast cancer with those of 353 control women to determine whether low levels of melatonin were associated with an increased risk for developing breast cancer.
They report in today's issue of the Journal of the National Cancer Institute (vol. 96, no 6, 475-482) that there was no evidence that the level of melatonin is strongly associated with the risk for breast cancer.
The hormone has been more widely investigated for its sleep-inducing effects as it is secreted by the pineal gland in the brain at night, and is an important regulator of circadian rhythms in the body, especially sleep. Supplements of melatonin have become popular in the US as a treatment for jet lag and insomnia. However in Europe and many other countries it is regulated as a medicine and requires a licence.
