Melatonin is a hormone naturally found in humans. Its association with cancer has been shown in many studies assessing links between shift work and cancer rates, and shown a consistent relationship. The association between melatonin levels and cancer progression has suggested to some that melatonin may be a modifier of cancer progression. In this latest study, researchers examined all clinical trials assessing the role of melatonin as a therapy for solid tumor cancers. They used a methodology called meta-analysis, a technique of analyzing multiple studies. The authors reviewed 10 randomized clinical trials that included a total of 643 cancer patients with a variety of different solid tumor cancers. The types of cancers involved included lung, brain, skin, renal and breast cancer. "In this analysis, the effects appeared to be consistent across studies" say the authors. The researchers examined the effect of large doses of melatonin (10-40mg/day) on survival rates at one year. Melatonin reduced the risk of death at one year by 34%. "Effects this large certainly warrant further clinical trials" say the authors. The study also showed that melatonin was predominantly safe and had a beneficial effect on sleep patterns of patients.
All of the clinical trials involved in their study were from Europe from a related network of clinical researchers in Italy and Poland. The researchers, from McMaster University and the University of Toronto in Canada, say that their analysis also shows that clinical trials in North America should have been initiated back in 1996/7 as the results from Europe were consistent at that time. The Canadian
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Contact: Edward Mills
millsej@mcmaster.ca
416-951-8530
McMaster University, Department of Clinical Epidemiology
22-Nov-2005