Melatonin Promising for Cancer Treatment

The role of melatonin for the treatment of cancer is appearing promising, according to a new study. Researchers reported that the findings are so convincing that cancer-funding agencies should be eager to support clinical trials to evaluate its therapeutic role in a number of cancers.

Melatonin is a hormone naturally found in humans. Its link with cancer has been demonstrated in many studies evaluating associations between shift work and cancer rates, and shown a consistent relationship. The link between melatonin levels and cancer progression has implied to some investigators that melatonin may be a modifier of cancer progression. In this latest study, researchers evaluated all clinical trials examining the role of melatonin as a therapy for solid tumor cancers. They used a methodology called meta-analysis, a technique of assessing 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, breast, and renal cancer. "In this analysis, the effects appeared to be consistent across studies,” reported the authors. The researchers examined the effect of large doses of melatonin (10-40 mg/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,” stated the authors in the study. 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 (Hamilton, Canada) and the University of Toronto (Canada), reported that their analysis also demonstrates that clinical trials in North America should have been started back in 1996/7 as the results from Europe were consistent at that time. The Canadian researchers, however, advise caution in interpreting the initial clinical usefulness of large doses of melatonin and recommend patients discuss this with their physicians before beginning any treatments.

Dr. Dugald Seely, a cancer researcher at Sick Children's Hospital (Toronto) and an author on the study, stated, "This analysis shows a strong association. The small number of people needed to treat, low adverse events reported, and low costs related to this intervention should be of substantial interest to patients, physicians, and policy makers. Completion of independently conducted studies is required to confirm the efficacy and safety of melatonin in cancer treatment.”

The researchers published their research in the November 2005 issue of the Journal of Pineal Research.





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