Washington, Mar 25: A team of scientists has developed a test that could help doctors precisely identify which breast cancer patients should receive aggressive therapy, thereby sparing many women at low risk for metastatic disease from undergoing unnecessary and potentially dangerous treatment.

Researchers developed the test based on an earlier finding that the co-mingling of three cell types can predict whether localized breast cancer will metastasize, or spread throughout the body.

Surgery is the first line of defence for most patients with breast cancer. For patients with higher-grade tumours, additional treatment with chemotherapy or radiation is typically recommended to decrease the risk that the disease will spread.

However, studies show that only 40 percent of these 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," said study co-author John S. Condeelis, Ph. D., professor and co-chair of anatomy and structural biology and co-director of the Gruss Lipper Biophotonics Center at Albert Einstein College of Medicine of Yeshiva University.

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 tumour 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. It could dramatically change the way we approach the care of women with breast cancer," said Condeelis.

While the new test promises to reduce overtreatment of breast cancer, it could reduce undertreatment as well.

"There are some patients with Grade 1 breast cancer who ultimately develop metastatic disease. By measuring TMEM counts, we could identify those people and treat them appropriately," said Condeelis.

The paper was published March 24th, 2009 in the online version of Clinical Cancer Research. (ANI)