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Predicting which breast cancers will spread

March 24, 2009 | 11:38 am

Breast1Women who are diagnosed and successfully treated for breast cancer often worry that the cancer has already spread to other parts of the body. Two papers published today provide hope that scientists will soon be able to better predict which cancerous tumors will metastasize and which are unlikely to grow beyond the localized tumor.

The first paper, published online today in the journal Clinical Cancer Research, advances a previous discovery by researchers at Albert Einstein College of Medicine of Yeshiva University. Recently, the scientists showed that a co-mingling of three types of cells can predict whether localized breast cancer will spread. Now the team, along with scientists at New York-Presbyterian Hospital/Weill Cornell Medical Center, has created a test for metastasis that can help doctors identify which patients should have aggressive treatments to prevent the spread of cancer and which patients can avoid further therapies.

The researchers previously found that a trio of cells present together in the same small area, called a microanatomic site, was predictive of metastasis. The cells are an endothelial cell, a perivascular macrophage (a type of immune cell) and a cell that produces a protein called Mena that enhances a cancer cell's ability to invade other tissues. A site with these three cells is called a tumor microenvironment of metastasis, or TMEM for short. In the current study, doctors tested breast tissue biopsy samples from 30 patients with advanced metastatic breast cancer and 30 patients with localized breast cancer, all of whom had been followed for at least five years. They found that TMEM density was much higher in patients who had developed metastatic disease.

"This is the first marker that could reliably predict metastatic outcome in a case-controlled study," John S. Condeelis, a co-author of the study, said in a news release. "It could dramatically change the way we approach the care of women with breast cancer."

The test could help doctors decide who needs additional therapy, such as radiation and chemotherapy, and who can skip these treatments. Traditionally, patients with "higher grade" tumors, which is based on the tumor's stage and other characteristics, are advised to undergo additional treatment to prevent metastasis. But studies show only 40% of those patients actually do develop metastatic disease. "What this means is that most of these patients are unnecessarily exposed to chemotherapy or radiation, which can have significant side effects or even worsen the disease," Condeelis said.

Other research is pointing to a new concept of metastasis for all types of cancers. Traditionally, doctors have assumed that metastasis occurs when a primary tumor grows so large that it develops characteristics allowing cells to invade other tissues in the body. However, the April issue of Nature Reviews Cancer offers a wholly different concept of metastasis that suggests it may occur much earlier in the course of the disease, when the tumor is small. Under this theory, tumor cells from even a small tumor migrate to other sites in the body, then develop traits that allow them to grow and survive. The theory is presented in a report by Christoph Klein of the University of Regensburg, Germany.

-- Shari Roan

Photo credit: National Cancer Institute

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