This pathway was identified in research with mice and substantiated in laboratory tests of human breast cancer samples. The findings appear in the September issue of the journal Cancer Cell.

The researchers found that, in mice, recurrent mammary tumors displayed characteristics of cellular changes previously linked with breast cancer. The tumors also had increased levels of a transcriptional repressor -- a gene that affects the activity of other genes -- called "Snail."

High Levels of 'Snail' Gene

Levels of Snail were sufficient to induce the cellular changes in primary breast cancer cells and to promote mammary tumor recurrence in mice, the study found.

When they screened human breast cancer samples, the researchers found that high levels of Snail expression also strongly predicted relapse in breast cancer patients.

New Generation of Cancer Drugs?

"While it is not possible to confirm a causal role for Snail in human breast cancer recurrence until drugs are available to inhibit this pathway, we believe that treatment of patients with pharmacologic agents that block Snail expression or function may be a promising approach to preventing breast cancer relapse," study leader Dr. Lewis A. Chodosh, of the University of Pennsylvania School of Medicine, said in a prepared statement.

"Snail may thereby represent an important target for a new generation of cancer therapeutics directed against specific molecules involved in breast cancer recurrence," Chodosh added.

More information: The American Cancer Society has more about breast cancer.