Stories of Impact

Breast cancer is the most common cancer among women worldwide and in the United States (except for non-melanoma skin cancer). To mark National Breast Cancer Awareness Month, we are highlighting AICR-supported research involving bacon, cholesterol and breast cancer. A scientist is investigating how a cholesterol by-product may play a role in recurrence and progression. 

Although metastatic breast cancer that spreads to other parts of the body is treatable, it may not be curable. Breast cancer cells that break away from the main tumor may settle in the bone marrow, liver or lungs. This can occur months or years after treatment, but little is known about why the cancer cells re-emerge.

“Funding from places like AICR really accelerates research and allows us to answer really important questions, which will ultimately change our approach to cancer.”

Can bacon fat promote breast cancer recurrence? AICR research is uncovering a possible link

Studies show that too much bacon and other high cholesterol foods are risks for cardiovascular disease. But can these foods also trigger dormant breast cancer cells to spread? Recent findings suggest they can, says Erik Nelson, PhD, Professor of Molecular and Integrative Physiology at University of Illinois at Urbana-Champaign. With grants from AICR, Dr. Nelson is uncovering how a cholesterol by-product and foods fried at high temperatures – such as bacon – may play a role in breast cancer recurrence.

Dr. Nelson honed in on a substance that cholesterol produces—a metabolite called 27HC—as a possible culprit in cancer progression. Researchers know that 27HC can both activate and block estrogen receptors in different areas of the body. Blocking estrogen activity is important for some breast cancers because when estrogen attaches to cell receptors, it fuels the growth of cancer cells. In breast cancer treatment, the drug Tamoxifen blocks estrogen from attaching to breast cancer cells. Yet it also activates estrogen in bone cells, which has positive effects.

The cholesterol metabolite 27HC was the first substance identified in the body that could have these dual functions.

Obesity, poor prognosis and cholesterol

Dr. Nelson published one of the major papers on 27HC in 2017. He wanted to understand the connection, if any, between this metabolite and why some breast cancers re-emerge after staying dormant. He suspected it had something to do with the association of breast cancer and obesity and, perhaps, high cholesterol.

He focused attention on several studies suggesting that breast cancer survivors who take statins, cholesterol-lowering drugs, have a longer recurrence-free survival time compared to those not prescribed a statin.

The cholesterol metabolite 27HC could be spurring cancer growth, Dr. Nelson hypothesized.

AICR studies: Bacon fat and mechanisms

Dr. Nelson and his colleagues first conducted lab studies that showed 27HC promoted tumor growth. In AICR-supported laboratory research, Dr. Nelson then investigated the effect of 27HC and a high-cholesterol diet on dormant breast cancer cells.

“We showed that 27HC dramatically promotes breast cancer metastasis; it can promote re-emergence from dormancy,” he said.

Currently, in another AICR-supported study, Dr. Nelson is investigating how preparing and cooking high-cholesterol foods—using bacon—may lead to cancer cells re-emerging from dormancy and promoting metastasis. Prior lab research found that a diet containing cured bacon fat increases metastasis compared to a lard and standard diet. (Lard is made using relatively low temperatures compared to bacon.) “What we don’t know is if it is the curing process or the cooking,” he said.

Dr. Nelson’s research has won him the $4.5 million Era of Hope Scholar Award from the U.S. Department of Defense (DoD) Breast Cancer Research Program, which recognizes innovative research that will lead to meaningful changes.

“The DoD grant allows us to piggyback on the AICR funding and instead of just looking at whether one food preparation technique is bad or good, it allows us to include additional groups and develop intervention strategies.”

Supporting research, advancing change

Dormancy is a particular problem in breast cancer since rogue cells can remain viable for many years. Dr. Nelson’s research offers hope to advance both dietary and pharmacological approaches for breast cancer survivors.

Adds Dr. Nelson: “Funding from places like AICR really accelerates research and allows us to answer really important questions, which will ultimately change our approach to cancer.”

Note: Dr. Nelson’s research is in its early stages. Currently, there are no prospective

clinical trials showing high cholesterol links to breast cancer recurrence or metastasis. For cancer prevention, AICR recommends that women diagnosed with breast cancer follow the same diet and lifestyle habits as the general population, when and if able. You can find those here.

Dr. Nelson recently represented AICR in the Rally for Medical Research, a virtual advocacy day involving researchers, clinicians, patients, caregivers, and advocates that is focused on increasing funding for biomedical research through the National Institutes of Health.  As part of that event, Dr. Nelson had an opportunity to share with Members of Congress and staff from his home state of Illinois information about his research and its impact on cancer prevention and survivorship through lifestyle.