New Breast Cancer Risk Identified: High Cholesterol

by PJ Hamel Patient Expert

Ever so gradually, researchers are identifying biological, environmental, and lifestyle factors associated with the onset or recurrence of breast cancer. Another element that may raise your risk has just been identified - and it's something many of us deal with every day.

High cholesterol. We all know it's a bad thing.

Most of us probably know our numbers; some may even know about LDL vs. HDL - which is the "good" cholesterol, which the "bad." We know that high cholesterol elevates our risk of cardiac issues and stroke. We know that certain foods we eat (red meat, full-fat dairy) can raise our bad cholesterol (LDL) numbers; while others (nuts, fish, whole grains) improve our cholesterol balance.

If we're trying to maintain a healthy lifestyle (eating right, exercising, not smoking, drinking in moderation), cholesterol is one of the basic markers we track, along with blood pressure, BMI (body mass index), and blood sugar.

Suddenly, tracking those cholesterol numbers may be just as important for breast health as for your heart and brain.

A study published online last month in the journal Science details a newly discovered relationship between high cholesterol and breast cancer risk. The Duke University study, based on mouse models and human breast cancer tumor cells, shows that a molecule called 27HC, which is a byproduct of cholesterol metabolism (it's produced as cholesterol grows), mimics the female hormone estrogen.

About 75% of breast cancers are estrogen-dependent (ER/PR+): they rely on estrogen to grow. Now, it appears not just estrogen, but 27HC helps breast cancer cells grow. Not only that, the study suggests that 27HC affects the cancer's aggressiveness; the higher the amount of 27HC, the more aggressive the cancer, and the more likely it is to spread.

One of the most effective treatments to lower risk of recurrence for women with ER/PR+ breast cancer is hormone therapy: tamoxifen for pre-menopausal women, an aromatase inhibitor (AI) for post-menopausal. In addition to fueling cancer's growth, it appears 27HC can cause women to develop resistance to tamoxifen; and may also reduce the effectiveness of AIs.

Bottom line, this molecule is potentially just as responsible for enabling breast cancer to grow and spread as estrogen. Which means as survivors with an ER/PR+ diagnosis, we need to be just as concerned with lowering 27HC as we are with eliminating estrogen.

These findings may be especially important to post-menopausal women taking an aromatase inhibitor. A women's level of cholesterol naturally rises during menopause; and AIs are also known to raise cholesterol levels, so this group of women is more likely to experience high levels of 27HC.

The results from this preliminary study are significant enough that researchers will now go beyond mice, and embark on a series of clinical trials using humans to prove or disprove the evidence gathered thus far.

In the meantime, if you're a breast cancer survivor - or simply a woman who'd like to lower her risk of breast cancer - here's something you can do:

Keep your cholesterol at healthy levels. Your goal is a total cholesterol level below 200; your LDL should be below 130, and your HDL, above 60. (Mayo, 2013)

Many of us can maintain good cholesterol levels through a healthy diet, exercise, and weight control.

Others, especially those with a genetic predisposition to high cholesterol, must take statin drugs: Lipitor, Crestor, Zocor, et. al. These drugs prevent the liver from making cholesterol, which forces it to remove cholesterol from your blood. The less circulating cholesterol in your body, the lower the amount of 27HC, the less fuel for cancer cells.

The American Heart Association's new guidelines around statins, also released last month, suggest that many more of us might benefit by taking the drugs, from a heart-health point of view. If future research supports current studies, those statins may be just as critical for preventing breast cancer as heart attacks.


High cholesterol fuels growth, spread of breast cancer. (2013, November 28). Retrieved from

Mayo Clinic Staff. (2013, February 12). High cholesterol. Retrieved from

Townsend, A. (2013, November 28). Breast cancer study findings: The "why" behind high cholesterol link; negative brca2 result not an "all clear" sign. Retrieved from

PJ Hamel
Meet Our Writer
PJ Hamel

PJ Hamel is senior digital content editor and food writer at King Arthur Flour, and a James Beard award-winning author. A 16-year breast cancer survivor, her passion is helping women through this devastating disease. She manages a large and active online survivor support network based at her local hospital and shares her wisdom and experience with the greater community via