Melatonin in the treatment of cancer: a systematic review of randomized controlled trials and meta-analysis

Authors

  • Edward Mills,

    1. Departments of Clinical Epidemiology & Biostatistics and Medicine, McMaster University, Hamilton, ON, Canada
    Search for more papers by this author
  • Ping Wu,

    1. London School of Hygiene and Tropical Medicine, University of London, London, UK
    2. Division of Clinical Epidemiology, Canadian College of Naturopathic Medicine, Toronto, ON
    Search for more papers by this author
  • Dugald Seely,

    1. Division of Clinical Epidemiology, Canadian College of Naturopathic Medicine, Toronto, ON
    2. Division of Hematology/Oncology, Sick Children's Hospital, University of Toronto, Toronto, ON, Canada
    Search for more papers by this author
  • Gordon Guyatt

    1. Departments of Clinical Epidemiology & Biostatistics and Medicine, McMaster University, Hamilton, ON, Canada
    Search for more papers by this author

Address reprint requests to Edward Mills, McMaster Health Sciences Centre, Department of Clinical Epidemiology and Biostatistics, Room 2C12, 1200 Main St. West, Hamilton, Ontario, Canada, L8N 3Z5.
E-mail: millsej@mcmaster.ca

Abstract

Abstract:  Most observational studies show an association between melatonin and cancer in humans. We conducted a systematic review of randomized controlled trials (RCTs) of melatonin in solid tumor cancer patients and its effect on survival at 1 yr. With the aid of an information specialist, we searched 10 electronic databases from inception to October 2004. We included trials using melatonin as either sole treatment or as adjunct treatment. Prespecified criteria guided our assessment of trial quality. We conducted a meta-analysis using a random effects model. We included 10 RCTs published between 1992 and 2003 and included 643 patients. All trials included solid tumor cancers. All trials were conducted at the same hospital network, and were unblinded. Melatonin reduced the risk of death at 1 yr (relative risk: 0.66, 95% confidence interval: 0.59–0.73, I2 = 0%, heterogeneity P ≤ 0.56). Effects were consistent across melatonin dose, and type of cancer. No severe adverse events were reported. The substantial reduction in risk of death, low adverse events reported and low costs related to this intervention suggest great potential for melatonin in treating cancer. Confirming the efficacy and safety of melatonin in cancer treatment will require completion of blinded, independently conducted RCTs.

Ancillary