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Meta Analysis/Melatonin

Meta Analysis/Melatonin


(August 24, 2005) – PHOENIX, AZ – The first meta-analysis examining the impact of melatonin on various cancers shows a strong association between the hormone’s use and a substantial improvement in survival after one year. A meta-analysis entails a process of using statistical methods to combine the results of different studies; the findings from this research effort, however, does include several important limitations

The results are based on a new study entitled, Melatonin in the Treatment of Cancer: A Systematic Review of Randomized Controlled Trials and Meta-Analysis. The Canadian research team is presenting its findings at the 20th Annual Meeting of the American Association of Naturopathic Physicians (AANP) http://www.naturopathic.org/. The meeting is being held August 24-26, 2005 at the Arizona Biltmore Hotel, Phoenix, AZ.


Melatonin is hormone made by the brain’s pineal gland. The hormone is widely known for its apparent impact on the body’s wake/sleep cycle, also called the circadian rhythm. Synthetic forms of melatonin are used to treat insomnia and jet lag.

The relationship between melatonin and cancer in human is less understood, although the majority of published reports demonstrate a positive interaction. There is also evidence that melatonin is beneficial during radiation therapy and chemotherapy.

Clinical trials have examining the impact of melatonin on solid tumors have yielded only ambiguous results. Accordingly, the research team conducted a systematic review and meta-analysis of the scientific literature for all randomized controlled trials (RCTs) involving the use of melatonin in the treatment of a variety of cancers, focusing on survival rates of individuals after one year.


All known research databases were searched in duplicate from the time of their respective inception until October 2004.From this information, the researchers selected RCTs which had enrolled patients diagnosed with cancer and survival rates at one year. Patients of any age, sex or stage of cancer diagnosis were included.


The researchers identified ten studies that met their analytic criteria. The studies had been published between 1992-2003, and included 643 patients.

The meta-analysis indicated a consistent effect on one year survival when melatonin was used as an adjunct therapy in a variety of advanced stage cancers; melatonin was well tolerated in all trials.

Limitations of the Study

The researchers tempered the value of these findings by underscoring two key limitations:
  • the same network of investigators in Italy and Poland conducted all ten trials. While this would not necessarily bias the results, the lack of independent verification warrants some uncertainty.


The American Association of Naturopathic Physicians (AANP) was founded in 1985 to provide alternative methods for healing human diseases and disorders than have been traditionally offered in the United States. Members of the AANP must have graduated from one of North America’s six accredited graduate schools of naturopathic medicine and served a clinical residency.

Editor’s Note: To schedule an interview with a member of the research team, please contact Donna Krupa at 703.527.7357 (office); 703.967.2751 (cell) or djkrupa1@aol.com.

For more information about naturopathic physicians, log on to http://www.naturopathic.org/.