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January 11, 2005

Northwestern Study Shows Why Olive Oil Protects Against Breast Cancer

CHICAGO --- Oleic acid, the main monounsaturated fatty acid contained in olive oil, can cripple a cancer gene that is responsible for 25 to 30 percent of all breast cancers, according to an article by Northwestern University researchers published in the Jan. 10 issue of the Annals of Oncology.

“These results lead us to an exciting path of inquiry about diet and breast cancer treatment and prevention,” said lead author Ruth Lupu, director of Evanston Northwestern Healthcare Breast Cancer Translational Research Program and professor of medicine at Northwestern University Feinberg School of Medicine.

Javier Menendez, research assistant professor at Feinberg and scientist at Evanston Northwestern Healthcare Research Institute, and Ramon Colomer, head of the medical oncology division at Institut Catala d’ Oncologia in Girona, Spain, were co-authors on the study.

“We observed that oleic acid not only suppressed the levels of the oncogene Her-2/neu but also improved the efficiency of the drug Herceptin™ (trastuzumab) that is already being used for the treatment of many women with breast cancer,” Lupu said. 

In a series of laboratory experiments on breast cancer cell lines, the expression of the breast cancer gene Her-2/neu was cut by more than 46 percent when treated with oleic acid.  Lupu and colleagues found that oleic acid not only suppressed the action of the oncogene, it also improved the effectiveness of the breast cancer drug Herceptin -- a targeted therapy that works against the Her-2/neu gene.

Breast cancer patients with Her-2/neu positive tumors suffer from an aggressive form of the disease and have a poor prognosis.

The study authors explained that the “power boost” that oleic acid provides to Herceptin is caused by DNA fragmentation, which promotes the death of cells that have amplified levels of Her-2/neu.  

“This study helps us understand how dietary fatty acids can regulate the growth and spread of breast cancer cells. It suggests to us that a diet rich in oleic acid, such as the Mediterranean diet, may delay or prevent Herceptin resistance in breast cancer patients who are Her-2/neu positive,” the authors said.

“Finding answers in the lab that can potentially improve clinical practice is the nature of translational research,” Leo Selker, president of the Evanston Northwestern Healthcare Research Institute.

Having a breast cancer translational research program in place provides patients with an added dimension of care, noted Janardan Khandekar, M.D., professor of medicine at Feinberg and chair, department of medicine, Evanston Northwestern Healthcare.

“New answers from research translate to better care for patients,” Khandekar said.