A new microfluidic device (above), developed by scientists at the University of Toronto, can measure estrogen levels in very small samples of tissue. The device, which will be used to monitor breast cancer patients, uses digital microfluidics, in which discrete droplets (colored with dyes in the picture) are manipulated on an open surface by application of electrical potentials to an array of electrodes. Credit: Aaron Wheeler

A microfluidics chip that can easily detect estrogen levels in breast cancer patients could give physicians a new way to monitor the disease. The chip, developed by scientists at the University of Toronto, uses electrical signals to move droplets of fluids around a microfluidics circuit, and it requires a blood or tissue sample 1,000 times smaller than that required by current methods. "If the technique becomes widely available, we could replace biopsies with pinpricks," says Aaron Wheeler, an engineer at the University of Toronto who developed the device.

The hormone estrogen plays a large role in many breast cancers, encouraging the growth of breast cancer cells. Some drugs such as Tamoxifen specifically block estrogen activity. The ability to routinely measure estrogen in breast tissue could give physicians a way of monitoring the effectiveness of cancer drugs, and it might even help assess the risk of recurrence or of developing the disease. "We have solid evidence that measuring estrogen inside the breast is important," says Noha Mousa, a physician at the University of Toronto who helped run the study. "If there is a high estrogen level, we know the drugs are not doing their job, and there is a likelihood of recurrence." However, estrogen isn't routinely measured in breast cancer patients because it requires a substantial tissue sample acquired through a painful and invasive biopsy.

Because the new chip takes such small samples, tissue can now be collected via a whisper-thin needle. In addition, the chip can measure estrogen levels in blood, saliva, or tissue, eliminating the preparation steps required by existing methods. "This device is the first we are aware of to accept raw unprocessed tissue as input, which we believe will eventually allow very quick turnaround," says Wheeler.

The device is still considered experimental, but Wheeler says his group is looking for funding to build a commercial prototype of the technology. He envisions two versions--one that would be used in a lab, and a smaller, point-of-care device that could be used in a doctor's office--and expects a commercial version to be available within the next five years.

Mousa plans to use the chip in a clinical trial funded by the Canadian Breast Cancer Foundation to measure hormone levels before and after treatment. "I believe this method will be useful for many applications in women's health," she says. "We can apply the same technique to many other steroid hormones."

She also hopes to use the technology to determine if estrogen levels in breast tissue of healthy women at risk for breast cancer can help predict their risk. "We have not been able to do that in healthy women because it requires taking a big sample," she says.