New UC Davis research supports the recent hypothesis that both ductal carcinoma in situ and invasive breast cancer develop from the same breast cancer progenitor cells. The research was reported at the annual meeting of the International Association for Breast Cancer Research in Montreal last month.

"The implication of these studies and others is that the genetic code for breast cancer is probably written at the pre-cancerous stage, so the rest is predestined," said Robert D. Cardiff, professor of pathology and director of the Mutant Mouse Pathology Lab at the UC Davis Center for Comparative Medicine. "This has profound implications for the prevention and treatment of breast cancer."

The conventional belief has been that DCIS, the most common form of localized breast cancer, spreads beyond the milk duct only if the DCIS cells are subjected to additional genetic damage. The newer hypothesis argues that breast cancer progenitor cells are present from the beginning in precancerous lesions, and are genetically programmed to progress not only to DCIS but also right on through to invasive breast cancer.

The UC Davis findings are based on studies in a line of transgenic mice engineered to develop mammary intraepithelial neoplasia, or MIN, the mouse equivalent of human DCIS.

The mouse model, developed by researchers at UC Davis and UC San Diego, is available only at UC Davis.

Cardiff, outgoing president of the International Association for Breast Cancer Research, summarized evidence for the new hypothesis in a presentation titled "Mammary Precancers: Old Concept and New Biology."

"The new hypothesis suggests that we are treating the wrong breast cancer cells," Cardiff said. "We need to determine how to correctly identify breast cancer progenitor cells in high-risk women and destroy these cells before they can become malignant."

At the Montreal meeting, four groups of UC Davis researchers reported o
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Contact: Claudia Morain
916-734-9023
University of California, Davis - Health System
6-Oct-2006