Copyright 1997 by Ralph W. Moss, Ph.D.

Many people with cancer are taking supplements of the pineal gland extract, melatonin. Are such patients--and especially women who have estrogen-receptor positive breast cancers, helped or harmed by taking this?

The whole subject is a relatively new one, and there is not a whole lot of data for us to rely on. Some of it comes from cell culture or epidemiological studies.

What does the record-to-date show about the relationship of melatonin to breast cancer?

About two-thirds of breast tumors are "estrogen-dependent," i.e., the female hormone estrogen accelerates the growth of such tumor cells. The exact way in which this happens is not known, but many such breast cancer cells have receptor sites, to which female sex hormone molecules attempt to bind.

When a female sex hormone molecule docks on the outside of such a cancer cell it may send a signal to that cell's DNA, telling it to divide. That is why anti-estrogens, such as the widely used drug tamoxifen, can slow the growth of hormone-dependent breast cancer cells.

But the presence of estrogen also seems to stimulate the production of another hormone, melatonin. Thus, melatonin may be the body's natural "answer" to excess estrogen. If so, then ingesting extra melatonin may counteract the undesirable effects of estrogen.

It has also been shown in the Lancet that there is a statistical correlation between a common malfunction of the pineal gland ("pineal calcification") and the incidence of breast cancer. These facts suggest a possibility that the less melatonin there is in a woman's blood, the greater her chances of breast cancer.

It is also interesting to note that:

· younger women, who have higher amounts of melatonin in their blood, have lower rates of breast cancer than older women;

· women who menstruate early in life have lower levels of melatonin and higher rates of breast cancer;

· psychiatric patients who take the drug Thorazine have lower rates of breast cancer. One of the things that Thorazine does is to raise blood levels of melatonin.

· Obese women, who have higher rates of breast cancer, also tend to have lower rates of melatonin.

· Blind women, who typically have higher rates of melatonin, have lower rates of breast cancer.


Adding melatonin to a cell line of cancer cells growing in a test tube (a strain called MCF-7) inhibited those cells by 78 percent. Melatonin also inhibited the growth of breast tumors in laboratory animals, either preventing the onset of a cancer of significantly slowing its growth.

Melatonin also blocked cell division in cancer cells. It interfered with "spindle formation," which happens to be the mechanism of action of the highly touted drug taxol.

It thus may be useful alongside this very toxic drug.


In their 1995 best-selling book, The Melatonin Miracle, Drs. W. Pierpaoli and W. Regelson, MD frightened some readers when they pointed out that "melatonin can increase the number of estrogen receptors on human breast cancer cells" (p. 120).

This sounds frightening, especially if you think that the more receptors a cell has, the greater its chances of accelerated cell growth.

However, the authors also point out that while an increase in the number of estrogen receptors on breast cancer cells seemingly would promote the growth of such cells, paradoxically--and for reasons unknown--"in melatonin's case it doesn't" (emphasis added).

It has also been shown that melatonin is a highly potent scavenger of harmful free radicals. It may protect DNA from the kind of damage that can add up to cancer.


In postmenopausal women, tamoxifen does indeed appear to extend lives. But over time, its beneficial effects may wear off. The same Drs. Pierpaoli and Regelson speculate that "it may be possible to give melatonin to women who do not have estrogen-sensitive cancers to induce the growth of estrogen receptors so that these women can also respond to tamoxifen."

It's a daring suggestion.

While not proven, "given the epidemic of breast cancer in the West," they say, "these ideas warrant further investigation."

In Italy, there have been a number of studies showing that people with advanced cancer may experience remissions (albeit mostly partial and/or temporary) after ingesting fairly high doses of melatonin. They also received relatively low dose injections of the well-known recombinant cytokine, interleukin-2 (IL-2).

Given the low cost and low toxicity of such a treatment, this Italian series of experiments deserves intensive examination.

Ralph W. Moss, Ph.D. is director of the The Moss Reports for cancer patients. Dr. Moss is the author of eleven books and three documentaries on cancer-related topics. He is or has been an advisor on alternative cancer treatments to the National Institutes of Health, the National Cancer Institute, the American Urological Association, Columbia University, the University of Texas, the Susan G. Komen Foundation and the German Society of Oncology. He wrote the first article on alternative medicine for the Encyclopedia Britannica yearbook. He is listed in Marquis Who's Who in America, Who's Who in the World, Who's Who in the East, and Who's Who in Entertainment (as a film documentarian). This Web site does not advocate any particular treatment for cancer. We urge you to always seek competent medical advice for all health problems, especially cancer. Before consulting our site please read our full Disclaimer statement.

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