Eating a diet high in broccoli and green tea may transform the most aggressive form of breast cancer into one that is highly treatable, say scientists at the University of Alabama at Birmingham. "Your mother always told you to eat your vegetables, and science now tells us she was right," said researcher Trygve Tollefsbol, Ph.D., D.O.

All breast cancers are either estrogen receptor-positive or estrogen receptor-negative. The tumors in estrogen receptor, or ER, negative breast cancer, don't respond as well to hormone therapy as tumors that are ER-positive. This means that ER-negative breast cancers are usually very aggressive.

"Unfortunately, there are few options for women who develop ER-negative breast cancer," says Tollefsbol. "Because of the poor prognosis this type of cancer carries, new advances in prevention and treatment for ER-negative breast cancer have particular significance."

Tollefsbol determined to find natural compounds that would efficiently neutralize processes that lead to, and worsen, ER-negative cancers. Until now, conventional cancer prevention has focused primarily on single chemopreventive compounds because researchers fear that combining compounds will lead to side effects, Tollefsbol said.

"To overcome that concern, we chose compounds that we felt confident would interact well together, because they have similar favorable biological effects but still have different mechanisms for carrying out these effects that would not interfere with one another."

Tollefsbol and his team identified two compounds in common foods that are known to have success in cancer prevention and that could potentially be combined to successfully “turn on” the ER gene in ER-negative breast cancer so that the cancer could be treated with estrogen receptor inhibitors such as tamoxifen.

The researchers found that a combination of dietary plant-derived compounds consisting of sulforaphane from cruciferous vegetables such as broccoli sprouts, along with polyphenols from green tea, is successful in preventing and treating ER-negative breast cancer in mice that are genetically programed to develop ER-negative breast cancer at high rates.

When the mice were treated with the sulforaphane/green tea combo, the tumors were converted from ER-negative to ER-positive cancers. This made the breast cancer easily treatable with tamoxifen, an estrogen receptor inhibitor.

The researchers hope that their study will eventually provide more effective treatment options for women who either have breast cancer or those who are predisposed to develop it.

About 12 percent of American women will develop breast cancer during their lifetime, and over 40,000 die from the disease each year.