Melatonin and Cancer

Dr. Weeks’ Comment: Melatonin, the naturally occurring hormone from your brain’s pituitary gland, is not just to help you sleep. It is a critically important benefit for preventing and treating cancer. 

“…On the basis of what is known about the context specificity of the actions of melatonin, it seems possible that melatonin may be useful in killing already damaged cancer cells while promoting the survival of injured normal tissue, i.e., both preventing or promoting anastasis depending on the cell type or circumstances. Certainly, the actions of melatonin are known to vary between cancer and normal cells. If melatonin is found to have such differential actions in cells that survive the harshest of conditions, it would have important implications in cancer therapies as well as in heart attack and stroke patients, etc.

. 2017 Apr; 18(4): 843.
Published online 2017 Apr 17. doi:  10.3390/ijms18040843
PMCID: PMC5412427

Melatonin, a Full Service Anti-Cancer Agent: Inhibition of Initiation, Progression and Metastasis

Andrzej Slominski, Academic Editor


There is highly credible evidence that melatonin mitigates cancer at the initiation, progression and metastasis phases. In many cases, the molecular mechanisms underpinning these inhibitory actions have been proposed. What is rather perplexing, however, is the large number of processes by which melatonin reportedly restrains cancer development and growth. These diverse actions suggest that what is being observed are merely epiphenomena of an underlying more fundamental action of melatonin that remains to be disclosed. Some of the arresting actions of melatonin on cancer are clearly membrane receptor-mediated while others are membrane receptor-independent and involve direct intracellular actions of this ubiquitously-distributed molecule. While the emphasis of melatonin/cancer research has been on the role of the indoleamine in restraining breast cancer, this is changing quickly with many cancer types having been shown to be susceptible to inhibition by melatonin. There are several facets of this research which could have immediate applications at the clinical level. Many studies have shown that melatonin’s co-administration improves the sensitivity of cancers to inhibition by conventional drugs. Even more important are the findings that melatonin renders cancers previously totally resistant to treatment sensitive to these same therapies. Melatonin also inhibits molecular processes associated with metastasis by limiting the entrance of cancer cells into the vascular system and preventing them from establishing secondary growths at distant sites. This is of particular importance since cancer metastasis often significantly contributes to death of the patient. Another area that deserves additional consideration is related to the capacity of melatonin in reducing the toxic consequences of anti-cancer drugs while increasing their efficacy. Although this information has been available for more than a decade, it has not been adequately exploited at the clinical level. Even if the only beneficial actions of melatonin in cancer patients are its ability to attenuate acute and long-term drug toxicity, melatonin should be used to improve the physical wellbeing of the patients. The experimental findings, however, suggest that the advantages of using melatonin as a co-treatment with conventional cancer therapies would far exceed improvements in the wellbeing of the patients.

for complete article  CLICK HERE 




2017 Jan;62(1). doi: 10.1111/jpi.12370. Epub 2016 Nov 25.

Cancer metastasis: Mechanisms of inhibition by melatonin.

Su SC1,2, Hsieh MJ3,4,5, Yang WE4,6, Chung WH1,2,7, Reiter RJ8, Yang SF4,6.


Melatonin is a naturally occurring molecule secreted by the pineal gland and known as a gatekeeper of circadian clocks. Mounting evidence indicates that melatonin, employing multiple and interrelated mechanisms, exhibits a variety of oncostatic properties in a myriad of tumors during different stages of their progression. Tumor metastasis, which commonly occurs at the late stage, is responsible for the majority of cancer deaths; metastases lead to the development of secondary tumors distant from a primary site. In reference to melatonin, the vast majority of investigations have focused on tumor development and progression at the primary site. Recently, however, interest has shifted toward the role of melatonin on tumor metastases. In this review, we highlight current advances in understanding the molecular mechanisms by which melatonin counteracts tumor metastases, including experimental and clinical observations; emphasis is placed on the impact of both cancer and non-neoplastic cells within the tumor microenvironment. Due to the broad range of melatonin‘s actions, the mechanisms underlying its ability to interfere with metastases are numerous. These include modulation of cell-cell and cell-matrix interaction, extracellular matrix remodeling by matrix metalloproteinases, cytoskeleton reorganization, epithelial-mesenchymal transition, and angiogenesis. The evidence discussed herein will serve as a solid foundation for urging basic and clinical studies on the use of melatonin to understand and control metastatic diseases.





 2012 Jun;21(6):819-31. doi: 10.1517/13543784.2012.681045. Epub 2012 Apr 16.

Melatonin uses in oncology: breast cancer prevention and reduction of the side effects of chemotherapy and radiation.



The possible oncostatic properties of melatonin on different types of neoplasias have been studied especially in hormone-dependent adenocarcinomas. Despite the promising results of these experimental investigations, the use of melatonin in breast cancer treatment in humans is still uncommon.


This article reviews the usefulness of this indoleamine for specific aspects of breast cancer management, particularly in reference to melatonin’s antiestrogenic and antioxidant properties: i) treatments oriented to breast cancer prevention, especially when the risk factors are obesity, steroid hormone treatment or chronodisruption by exposure to light at night (LAN); ii) treatment of the side effects associated with chemo- or radiotherapy.


The clinical utility of melatonin depends on the appropriate identification of its actions. Because of its SERM (selective estrogen receptor modulators) and SEEM (selective estrogen enzyme modulators) properties, and its virtual absence of contraindications, melatonin could be an excellent adjuvant with the drugs currently used for breast cancer prevention (antiestrogens and antiaromatases). The antioxidant actions also make melatonin a suitable treatment to reduce oxidative stress associated with chemotherapy, especially with anthracyclines, and radiotherapy.

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