According to a news release from Duke University Medical Center, a side product of cholesterol acts like the hormone estrogen to incite the development and spread of the most common kinds of breast cancers.

The researchers also discovered that anti-cholesterol drugs, like statins, seem to decrease the impact of this estrogen-like molecule.

The results for the first time go into detail about the link between high cholesterol and breast cancer, especially in post-menopausal women, and imply that dietary alterations or therapies to lower cholesterol may also provide a simple method to decrease breast cancer risk.

“A lot of studies have shown a connection between obesity and breast cancer, and specifically that elevated cholesterol is associated with breast cancer risk, but no mechanism has been identified,” said senior author Donald McDonnell, chair of the Department of Pharmacology and Cancer Biology at Duke, in a statement. “What we have now found is a molecule – not cholesterol itself, but an abundant metabolite of cholesterol – called 27HC that mimics the hormone estrogen and can independently drive the growth of breast cancer.”

According to researchers, the hormone estrogen fuels approximately 75 percent of all breast cancers. Earlier research from McDonnell’s lab revealed that 27-hydroxycholesterol – or 27HC – acted similarly to estrogen in animals.

For this study, the researchers wanted to figure out whether this estrogen activity was adequate on its own to advance breast cancer development and metastasis, and whether managing it would have an opposite effect.

Utilizing mouse models that are very predictive of what takes place in humans, the researchers revealed the direct involvement of 27HC in breast tumor development, as well as the aggressiveness of the cancer to expand to other organs. They also found that the activity of this cholesterol metabolite was restricted when the animals were treated with antiestrogens or when the augmentation of 27HC was halted.

The research was affirmed utilizing human breast cancer tissues. An additional discovery in the human tissue revealed a direct correlation between the aggressiveness of the tumor and a great amount of the enzyme that produces the 27HC molecule. They also found that 27HC could be produced in other places in the body and moved to the tumor.

“The worse the tumors, the more they have of the enzyme,” said lead author Erik Nelson, a post-doctoral associate at Duke.

“This is a very significant finding,” McDonnell added. “Human breast tumors, because they express this enzyme to make 27HC, are making an estrogen-like molecule that can promote the growth of the tumor. In essence, the tumors have developed a mechanism to use a different source of fuel.”

According to the researchers, the results imply there may be an easy method of lowering the risk of breast cancer by maintaining a healthy cholesterol level.

The study’s findings are described in greater detail in the journal Science.