According to MedlinePlus, melatonin is a naturally occurring hormone that regulates the sleep cycle. It is often taken as a supplement for the self-treatment of insomnia. Receptors for melatonin are found throughout the body, and this hormone has diverse regulatory roles in numerous organ systems, including the digestive tract and the immune system. Melatonin can also act as an antioxidant agent. Melatonin is being researched as of early 2011 for its role in cancer progression and its ability to suppress cancer development.
Circadian Rhythms
The circadian rhythm is the internal clock that regulates sleep patterns. According to the October 2006 issue of "Cancer Research," Dr. Brittney Jung shows that the incidence of certain cancers can be associated with alterations in normal sleep cycle. Melatonin, an important regulator of circadian rhythms, is highly unstable in light. Under large light, melatonin levels in the body will decrease. It is this way that melatonin regulates our sleep cycle. Excessively low melatonin levels can have an important biological impact that could increase cancer incidence.
Time Dependence
Because melatonin is unstable in light, in the October 2006 issue of "Cancer Research," Dr. Brittney Jung suggests that the success of melatonin as an anti-cancer agent is time-dependent and most effective at night. It is also suggested that differences in administration time of melatonin may account for some of the diverse, inconsistent laboratory data of this supplement against various cancer types. Animal cancer studies support the time-dependent effect of melatonin. Most clinical trials also have adopted this time dependent effect, administering the supplement only at night.
Breast Cancer
According to Jung, breast cancer patients, in general, have lower levels of melatonin in the blood. Lower melatonin levels also correlate with greater tumor size in patients with breast cancer. It is thought that decreased melatonin will lead to increased estrogen, which in turn can cause rapid unwanted growth of breast stem cells, increasing the chance of malignant cells' development. Clinically, a 20 mg dose of melatonin at night successfully increased the responsiveness of patients with metastatic breast cancer to tamoxifen, a chemotherapeutic medication.
Brain Metastases
In a clinical study published in the February 1994 edition of "Cancer," 50 patients suffering from brain metastases, secondary tumor lesions derived from other solid tumors, were randomly separated into two research groups. Group one received only supportive care for the brain metastases that included steroids and anti-seizure medication. Group two received supportive care and a nightly 20 mg dose of melatonin. Melatonin increased patient survival rate past one year by 26 percent. Patients who also received melatonin exhibited overall decreased mortality.
Adverse Reactions
Although the data is promising for melatonin as potential cancer treatment, more research is necessary to determine the effectiveness or possible side effects of this supplement in regards to cancer treatment. Melatonin can interact with numerous medications. Because melatonin can act as an anti-oxidant compound, it can also potentially inhibit the cytotoxic effects of known chemotherapy drugs. First consult a doctor before using melatonin, and do not use this supplement as an alternative to more-orthodox cancer medication.
References
- MedlinePlus: Melatonin
- "Immunology"; Melatonin -- a Pleiotropic Molecule Involved in Pathophysiological Processes Following Organ Transplantation; James E Fildes, Nizar Yonan, and Brian G Keevil; August 2009
- "Cancer Research"; Melatonin in Cancer Management: Progress and Promise; Brittney Jung and Nihal Ahmad; October 2006
- "Cancer"; A Randomized Study with the Pineal Hormone Melatonin Versus Supportive Care Alone in Patients with Brain Metastases Due to Solid Neoplasms; Lissoni P, Barni S, Ardizzoia A, Tancini G, Conti A, and Maestroni G; February 1994
