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Thursday, September 30, 2010

Screening for HER2 breast cancer

There are different types of breast cancer, some much more aggressive than others. There are also a variety of treatment regiments, so identifying the type of cancer quickly and accurately is critical. To complicate matters further, tumors that develop from circulating cancer cells are not always identical to the original tumor. Until recently, it has been impossible to screen blood for elusive, migrating cancer cells. Now, Benjamin Thierry and colleagues from the University of South Australia have developed a device for screening cancer cells circulating in blood.

In particular, the researchers were looking for ways to determine whether patients were positive for HER2, a protein associated with a very aggressive type of breast cancer. If these patients are treated early enough with the HER2 blocker trastuzumab (Herceptin), their prognosis improves tremendously. However, at over $50,000/year, Herceptin is too expensive to give to every breast cancer patient, considering that only the 20 to 25% of patients who overexpress HER2 would benefit.

Traditionally, HER2 status is determined via biopsy of the primary breast tumor. As I stated, this can yield misleading results. Twenty percent of the time, secondary tumors that result from metastasis do not match the primary tumor. In order to be certain whether or not a patient will benefit form Herceptin, doctors must isolate and test all circulating cancer cells as well as the primary tumor, something that has been impossible.

To that end, Thierry and his team have developed a disposable microfluidic device that can capture cancer cells but not normal blood cells. When tested in breast cancer cell lines, the device captured about 80% of cancer cells circulating in blood samples. If the device is equally effective in human trials, it means that doctors will be much closer to knowing whether any cells in their patients’ bodies would respond to Herceptin treatment, knowledge that could save many lives.

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