Researchers at the University of Michigan Comprehensive Cancer Center have found that when the dietary compounds curcumin, the derivative of the Indian spice turmeric, and piperine, the derivative of black peppers, were applied to breast cells in culture, they decreased the number of stem cells while not affecting normal differentiated cells. The researchers also suppose that by limiting the number of stem cells they can limit the number of cells, which might produce tumors.

Cancer stem cells are located within a tumor and thus fuel the tumor's growth. Current chemotherapies do not work against these cells, which is leading to cancer’s spread. Researchers believe that purging the cancer stem cells is the key to cancer’s control. In addition, decreasing the number of normal stem cells, the ones that can give rise to any kind of cell in that organ, can decrease the risk of cancer.

The researchers applied a series of tests to the cells, looking at markers for breast stem cells and the effects of curcumin and piperine on the stem cell levels. They found that piperine improved the effects of curcumin, and that the compounds interrupted the self-renewal process. At the same time, the compounds had no affect on cell development. As appears, these compounds are not toxic to normal breast tissue. Such drugs as tamoxifen or raloxifene are being used for breast cancer prevention, but most women won't take these drugs because there is too much toxicity. Dietary compounds on the contrary have very low toxicity.

In addition, tamoxifen or raloxifene are designed to affect estrogen, which is a factor in most of the breast cancers. In fact, the aggressive tumors that tend to occur in women with a family history or genetic vulnerability are typically not affected by estrogen. Because curcumin and piperine bound the self-renewal of stem cells, they would force cancers that are not estrogen sensitive as well as those that are.

Researchers are planning an initial Phase I clinical experiment to determine what dose of curcumin or piperine can be tolerated in people. The trial is not expected to begin accruing participants until spring.

Breast cancer statistics: 194,280 Americans will be diagnosed with breast cancer this year and 40,610 will die from the disease, according to the American Cancer Society.