Scrutinizing the evidence for breast
cancer procedures and treatments

Melatonin is a
hormone produced in
the pineal gland
located in the brain.
It is best known for its
role in the regulation of
the sleep/wake cycles.

An Overview of
Melatonin and Breast
Cancer by Tina
Kaczor, ND

Dosage: Melatonin can
be safely taken for an
indefinite dose of
melatonin for breast
bedtime.  Some people
initially experience
vivid dreams or
morning drowsiness.
To avoid slowly
increased over a
period of several
weeks. Consult your
doctor before starting
this or any supplement
--Life Extension
  Breast cancer supplement strategy - raising Melatonin levels?

    Laboratory experiments have found that low levels of melatonin stimulate the growth of
    certain types of breast cancer cells.  Researchers found adding melatonin to these cells
    inhibits their growth. Melatonin is widely recommended because it has several beneficial
    methods of action.

  • A high number of women with estrogen receptor positive tumors have
    low levels of melatonin in their blood.

  • Melatonin appears to work as an anti-estrogen on tumor cells. although
    differently than Tamoxifen. When the two are combined, the result is better
    than Tamoxifen alone. (Lissoni et`al., 1995.)

  • A 2006 study showed Melatonin may work as a kind of aromatase
    inhibitor. (Cos et al.)

  • Low levels of melatonin have been associated with breast cancer
    occurrence and development. Women who work predominantly at night
    and are exposed to light, which inhibits melatonin production and alters
    the circadian rhythm, have an increased risk of breast cancer
    development (Schernhammer et al. 2003).

  • The circadian rhythm alone is a  significant predictor of survival time for
    breast cancer patients (Sephton et al. 2000).

  • Melatonin demonstrates growth inhibitory effects by inducing
    differentiation (“normalizing” cancer cells)(Cos et al. 1996) as well directly
    inhibits breast cancer cell proliferation (Ram et al. 2000) and  boosting the
    production of immune components, including natural killer cells (NK cells)
    that have an ability to kill metastasized cancer cells.

    Melatonin can be safely taken for an indefinite period of time. The
    suggested dose of melatonin for breast cancer patients is 3-50 mg at
    bedtime.  Some people initially experience vivid dreams or morning
    drowsiness. To avoid these minor side effects melatonin may be taken in
    low doses nightly and the dose slowly increased over a period of several
    weeks. Consult your doctor before starting this or any supplement.
                Interesting research on Melatonin

    Curr Med Chem. 2010;17(36):4462-81.

    Basic mechanisms involved in the anti-cancer effects of melatonin.

    Mediavilla MD, Sanchez-Barcelo EJ, Tan DX, Manchester L, Reiter RJ.

    Department of Physiology & Pharmacology, School of Medicine, University of Cantabria,
    39011 Santander, Spain.

    It is commonly accepted that melatonin (N-acetyl-5-methoxytryptamine), the most relevant
    pineal secretory product, has oncostatic properties in a wide variety of tumors and,
    especially, in those identified as being hormonedependent. The objective of the present
    article is to offer a global and integrative view of the mechanisms involved in the oncostatic
    actions of this indoleamine. Due to the wide spectrum of melatonin's actions, the
    mechanisms that may be involved in its ability to counteract tumor growth are varied. These
    include: a) antioxidant effects; b) regulation of the estrogen receptor expression and
    transactivation; c) modulation of the enzymes involved in the local synthesis of estrogens; d)
    modulation of cell cycle and induction of apoptosis; e) inhibition of telomerase activity; f)
    inhibition of metastasis; g) prevention of circadian disruption; h) antiangiogenesis; i)
    epigenetic effects; j) stimulation of cell differentiation; and k) activation of the immune
    system. The data supporting each of these oncostatic actions of melatonin are summarized
    in this review. Moreover, the list of actions described may not be exhaustive in terms of how
    melatonin modulates tumor growth.

    Epidemiology. 2006 Jan;17(1):108-11.

    Night work and risk of breast cancer.

    Schernhammer ES, Kroenke CH, Laden F, Hankinson SE.

    Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard
    Medical School, Boston, Massachusetts 02115, USA. eva.schernhammer@channing.harvard.

    BACKGROUND: Melatonin shows potential oncostatic activity and is acutely suppressed by
    light exposure. Some evidence suggests an association between night work and breast
    cancer risk, possibly through the melatonin pathway. METHODS: In a cohort of
    premenopausal nurses, we prospectively studied the relation between rotating night shift
    work and breast cancer risk. Total number of months during which the nurses worked
    rotating night shifts was first assessed at baseline in 1989 and periodically updated
    thereafter. We used Cox proportional hazards models to calculate relative risks (RRs) and
    95% confidence intervals (CIs). RESULTS: Among 115,022 women without cancer at baseline,
    1,352 developed invasive breast cancer during 12 years of follow up. Women who reported
    more than 20 years of rotating night shift work experienced an elevated relative risk of
    breast cancer compared with women who did not report any rotating night shift work
    (multivariate RR = 1.79; 95% CI = 1.06-3.01). There was no increase in risk associated with
    fewer years of rotating night work. CONCLUSION: Our results suggest a modestly elevated
    risk of breast cancer after longer periods of rotating night work. Additional studies are
    warranted to rule out small sample size or uncontrolled sources for confounding as
    alternative explanations..

    Melatonin increases the survival time of animals with untreated mammary tumours:
    neuroendocrine stabilization.

    Saez MC, Barriga C, Garcia JJ, Rodriguez AB, Masot J, Duran E, Ortega E.

    Department of Physiology, Faculty of Science, University of Extremadura, Badajoz, Spain.

    The aim of this study was to evaluate the therapeutic effect of melatonin, the main hormone
    of the pineal gland, on rats with advanced and untreated mammary tumours. Mammary
    tumours were chemically induced in Sprague-Dawley rats with the carcinogen 9,10-dimethyl-
    1,2-bezanthracene (DMBA). After the appearance of tumours the effect of melatonin (5 mg/ml
    per rat per day) was then evaluated on the survival time, tumour multiplicity, and tumour
    volume until the death of the animals. In addition, the variations in prolactin, noradrenaline
    and adrenaline concentrations, and in the percentage of NK cells were evaluated after one
    month of the treatment with melatonin. Daily administration of melatonin increased
    significantly the survival time of tumour-bearing animals (p<0.05 with respect to the control
    non-melatonin-receiving rats). The increased survival time did not correlate, however, with
    changes in either tumour multiplicity or tumour growth rate. Animals with mammary tumours
    exhibited an increase (p<0.05 with respect to healthy animals) in prolactin and
    catecholamine concentrations. The administration of melatonin stabilized the hormone
    levels, returning them to those in the basal-healthy animals. Rats with mammary tumours
    also presented lower percentages of NK cells, which were not increased by the
    administration of melatonin. The results strongly suggest that melatonin per se is beneficial
    during advanced breast cancer. It increases survival time, maybe by improving the
    homeostatic and neuroendocrine equilibrium which is imbalanced during advanced breast

    Int J Cancer. 2006 Jan 15;118(2):274-8.

    Melatonin inhibits the growth of DMBA-induced mammary tumors by decreasing the local
    biosynthesis of estrogens through the modulation of aromatase activity.

    Cos S, Gonzalez A, Guezmes A, Mediavilla MD, Martinez-Campa C, Alonso-Gonzalez C,
    Sanchez-Barcelo EJ.

    Department of Physiology and Pharmacology, School of Medicine, University of Cantabria,
    Santander, Spain.

    Melatonin inhibits the growth of breast cancer cells by interacting with estrogen-responsive
    pathways, thus behaving as an antiestrogenic hormone. Recently, we described that
    melatonin reduces aromatase expression and activity in MCF-7 human breast cancer cells,
    thus modulating the local estrogen biosynthesis. To investigate the in vivo aromatase-
    inhibitory properties of melatonin in our current study, this indoleamine was administered to
    rats bearing DMBA-induced mammary tumors, ovariectomized (ovx) and treated with
    testosterone. In these castrated animals, the growth of the estrogen-sensitive mammary
    tumors depends on the local aromatization of testosterone to estrogens. Ovariectomy
    significantly reduced the size of the tumors while the administration of testosterone to ovx
    animals stimulated tumor growth, an effect that was suppressed by administration of
    melatonin or the aromatase inhibitor aminoglutethimide. Uterine weight of ovx rats, which
    depends on the local synthesis of estrogens, was increased by testosterone, except in those
    animals that were also treated with melatonin or aminoglutethimide. The growth-stimulatory
    effects of testosterone on the uterus and tumors depend exclusively on locally formed
    estrogens, since no changes in serum estradiol were appreciated in testosterone-treated
    rats. Tumors from animals treated with melatonin had lower microsomal aromatase activity
    than tumors of animals from other groups, and incubation with melatonin decreased the
    aromatase activity of microsomal fractions of tumors. Animals treated with melatonin had
    the same survival probability as the castrated animals and significantly higher survival
    probability than the uncastrated. We conclude that melatonin could exert its antitumoral
    effects on hormone-dependent mammary tumors by inhibiting the aromatase activity of the
    tumoral tissue.
Breast Cancer ChoicesTM

    This website is intended as information only. The editors of this site are not medically-trained.
    Please consult your licensed health care practitioner before implementing any health strategy.

    The information provided on this site is designed to support, not replace, the relationship that
    exists between a patient/site visitor and his/her existing physician. This site accepts no
    advertising. The contents of this site are copyrighted 2004-2013 by Breast Cancer Choices,
    Inc., a 501 (c) (3) nonprofit organization run entirely by unpaid volunteers.
    Contact us with comments or for reprint permission at admin@breastcancerchoices.org

    Web page updated March 2013
Home    FAQ    Strategies    Discussion    Iodine   Hormones    Contact    Store