Melatonin: Potential Anti-Cancer Effects

The hormone melatonin has long been used to help improve sleep.¹

But its effects go much further.

Scientists have found that taking oral melatonin may influence many physiological processes that could potentially provide anti-cancer benefits.^2-5

Oral melatonin has been shown in clinical studies to reduce side effect severity when taken along with conventional cancer treatments.^2,5-7

Even more impressively, in multiple studies of cancer patients, adding melatonin to standard treatment improved tumor regression and survival rates.

Too Much Light!

When we are exposed to regular light and dark cycles, our bodies produce and release the hormone melatonin mostly at night in the dark.^2,4

Melatonin helps induce and control sleep. But it determines much more than just sleep/wake cycles: It affects hormone levels, immune function, inflammation, reproduction, and cell protection^4,8 One of its important roles is DNA protection and repair.^3,9

These days, many people get too much artificial light exposure in the evenings, whether from overnight work shifts, late night television watching, or staying up looking at phones, tablets, or computer screens.

This disrupts the natural light and dark cycle and can cause melatonin levels to plunge.¹⁰ To make matters worse, melatonin secretion also tends to diminish with older age.¹¹

Disruption of this natural cycle and of melatonin secretion has negative effects throughout the body. Research has shown that taking oral melatonin at night may help mitigate these problems, aiding sleep and activating the hormone’s other vital functions.

Anti-Cancer Actions

Preclinical data have shown that melatonin can regulate different physiological pathways in the body that can help protect against cancer. These include inhibition of tumor cell growth, promotion of immune cell response, and enhanced apoptosis (normal cell death).¹²

Three pathways involved in these effects include:

1. Signaling Pathways. In preclinical studies melatonin has been shown to inhibit malignant transformation of healthy cells by downregulating growth factors, suppressing tumor progression, and initiating apoptosis.² Studies on breast cancer cells and animals have reported melatonin combined with chemotherapy treatment showed improved apoptotic effects compared to melatonin alone.⁸
2. Supporting healthy immune function. Preclinical studies have shown that melatonin plays an instrumental role in modulating immunity, which suggests potential as an adjuvant against certain viral and bacterial infections.^13-15 Modulation of immune response has potential to enhance the effectiveness of anti-tumor therapy and ease normal tissue toxicity.¹⁶ This immune-modulating property of melatonin may also help the immune system identify and target cancerous and precancerous cells, meaning it might be able to impede the growth of cancerous cells and reduce tumor size.^8,16
3. Oxidative stress. Oxidative stress can cause DNA damage, increasing the risk of cancer. The antioxidant activity of melatonin is a protective mechanism that might reduce cancer risk and progression.^2,9

Through these and other actions, melatonin has been shown to have anti-cancer effects on cancer cell lines, including:

• Prostate,^8,17
• Breast,^8,17
• Stomach,^2,17
• Lung,^5,18
• Ovarian,^5,8
• Colorectal,^5,17
• Oral,^2,5
• Liver,^8,12 and
• Kidney.⁵

Improving Response to Human Standard Treatment

Observational studies have shown that exposure to light at night is associated with increased risk of breast cancer. And suppression of melatonin is believed to play an important role in this association.^19-21

Human studies have reported that lower levels of urinary melatonin metabolites are associated with increased risk of advanced prostate²² and breast cancer.²³

One study evaluated women with estrogen receptor negative ER (-) metastatic breast cancer. These women had late-stage advanced disease and could not tolerate further chemotherapy (due to age, low performance status) and/or had previously received chemotherapy.²⁴

They were randomized to receive 20 mg of melatonin or a placebo nightly, in addition to the cancer medication tamoxifen. For such aggressive cancer, the outcomes were remarkable:²⁴

• The tumor response rate, the percentage of patients who had improvement in their cancer, was significantly better in those receiving melatonin and tamoxifen.
• The one-year survival rate more than doubled in those taking melatonin.

Several other studies in cancer patients have shown benefits of melatonin added to treatments such as immunotherapy or chemotherapy.^{2,6,7,18,25-28}

In one of these studies, patients with metastatic solid tumors of various types were randomized to receive chemotherapy alone, or 20 mg of melatonin daily in addition to their chemotherapy. The one-year survival rate and rate of tumor regression was higher with melatonin, with positive outcomes approximately doubled.²⁸

Another study of patients with cancer that had metastasized to the brain showed that taking melatonin improved one-year survival rates and mean survival times.²⁶

Meta-analyses of human trials have shown that cancer patients taking melatonin along with conventional treatment had better survival rates and tumor response rates than patients who don’t receive melatonin.^6,7,25

These studies show that melatonin, when taken with standard cancer treatment, may enhance the efficacy of chemotherapy and mitigate side effects.

Easing Side Effects

Melatonin may also help minimize the negative effects of cancer treatments.²⁹

A review of human studies showed that melatonin may improve sleep quality and insomnia in patients with cancer.³⁰

In one trial of women with breast cancer, the treatment group received 18 mg of melatonin daily, beginning one week prior to the treatment until two years after completion. After two years researchers concluded that long-term use of melatonin decreased the level of fatigue, which is common in cancer patients undergoing cancer treatment.³¹

Impaired cognitive function is a common side effect of chemotherapy. In a randomized controlled trial in women undergoing chemotherapy for breast cancer, 20 mg of daily melatonin was taken before and during their first cycle of chemotherapy. Those who received melatonin experienced improvement in several markers of cognitive function as compared to placebo. In addition, there was improvement in sleep quality and reduction in symptoms of depression, compared to placebo.³²

Many chemotherapy and radiation treatments also cause potentially lethal side effects. Studies have found that melatonin protects against many of these, including low platelet counts, neurotoxicity and cardiotoxicity, weakness, and more.^6,7,31,32

Melatonin has been shown to augment some cancer therapies and protect against harmful side effects of treatment.

Summary

The hormone melatonin exhibits anti-cancer properties.

Human observational studies have shown lower levels of urinary melatonin are associated with increased risk of advanced prostate and breast cancer.

Studies of patients with existing cancer show that taking oral melatonin may increase survival rate, improve tumor response, and protect against side effects of other cancer treatments.

If you have any questions on the scientific content of this article, please call a Life Extension Wellness Specialist at 1-866-864-3027.

References

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