Elise Fear and Jie Chen are developing a pair of painless cancer-fighting techniques, one to diagnose the disease and another to treat it.
Fear, an IEEE member and an associate professor of electrical engineering at the University of Calgary’s Schulich School of Engineering, in Alberta, Canada, is using three-dimensional microwave imaging to detect breast tumors. She hopes the technique eventually will replace mammography machines and their painful breast compression.
Chen, a senior member and an associate professor in the department of electrical and computer engineering at the University of Alberta in Edmonton and a research officer at the Canadian National Institute of Nanotechnology, is using nanotechnology to target and kill cancer cells but spare normal cells, reducing the unpleasant side effects of radiation treatment.
MORE PLEASANT EXPERIENCE
Getting a mammogram can be uncomfortable, most women say. That’s because the breasts must be compressed and flattened to fit into the X-ray machine. Fear’s alternative is to use low-power radar as a diagnostic tool. Called tissue-sensing adaptive radar (TSAR), the process involves illuminating each breast with a pulse of radio-frequency energy and sensing the reflections to create a 3-D image. The patient lies on her stomach on a table with her breast extending through an opening into a tank filled with clear canola oil. The nontoxic oil cuts down on the microwaves being reflected from the skin, allowing for a better image than if the breast was in air.
A sensor emits short pulses of microwaves into the oil and “listens” for the reflections from the breast. Located inside the tank, the sensor moves around, and up and down, so as to scan the entire breast. TSAR uses differences in electromagnetic properties of healthy and diseased tissue to form images, which are examined to detect small tumors and to determine their location. TSAR uses much lower power signals than even a cellphone, Fear says.
“We scan the sensors around the breast, collecting about 200 reflections in total, and process these reflections to form an image,” she says. “Reflections from tumors are different than reflections from healthy tissue. Microwave breast imaging tries to identify differences that can be quite small but shouldn’t be there.”
Medical technologies can take more than 25 years to develop before they can be used on patients; TSAR is in year 11 and on its third prototype. Clinical trials are being conducted, with scans so far of 13 patients. More patients are being recruited in Calgary by the Foothills Medical Centre, which has partnered with the university.
So far feedback from the volunteers has been positive, Fear says. “We thought the oil would be messy and unappealing,” she says, “but it turns out it cleans up fairly easily, and the patients haven’t complained about it. Many actually enjoy the scan.”
SMALL BUT POWERFUL
In his work, Chen is using nanoparticles, which are 10 000 times smaller than a human cell, to develop new treatments, allowing radiation to selectively target cancer cells. The technique could ease the suffering caused by traditional radiation, or radiotherapy, and might someday lead to earlier detection of tumors.
Because cancer cells undergo faster metabolism than normal cells, they require more glucose to fuel their growth. Chen relies on glucose-capped, gold-based nanoparticles (GLU-GNPs). “We discovered that cancer cells uptake significantly more glucose-coated GNPs than normal cells, a difference that can be harnessed to achieve targeted cancer radiotherapy with fewer side effects for healthy tissue,” Chen says. “For instance, breast-cancer cells uptake 10 times more GLU-GNPs than normal breast tissue, so that for the same dose of radiation, cancer cells suffered more than 10 times the damage of normal tissue, while minimizing the damage to healthy tissue."
Also, gold is a bio-friendly metal, remaining relatively inert inside the body.
The nanoparticles are injected into an artery. While circulating in the bloodstream, the GLU-GNPs are selectively taken in by cancer cells. During treatment, radiation parameters are precisely tailored according to factors such as the stage of cancer, tumor size, and location.
“These tiny nanoparticles behave as beacons, focusing radiation at cancerous cells while leaving surrounding tissue unharmed, thus negating the need for the large-beam dosage used in traditional radiation treatment,” Chen says. “Usually, radiation not only wipes out the tumor but also damages normal cells, resulting in severe side effects such as hair loss, nausea, and vomiting. Our nanoparticle-based treatment increases targeting specificity for more effective irradiation.”
Chen’s team conducted studies on mice that showed most of the gold is evacuated from the body through the urine, and the remaining nanoparticles cause no damage to cells or induce any abnormal behavior. “Any side effects would be caused by the radiation, not the gold nanoparticles,” he says.
He says his treatment in conjunction with traditional radiotherapy significantly reduces the radiation dose needed for eradication of tumors, leading to faster recovery with fewer side effects.
In 2009, he and other researchers at the University of Alberta filed a U.S. patent for the procedure. Once studies on animals are completed, they plan to apply to the U.S. Federal Drug Administration to begin clinical trials, which are expected to start next year.
“Because our procedure is not limited to a specific type of cancer, it offers great potential,” Chen says.
He is also working on another application of diagnostic imaging that binds positron-emission-tomography tracers onto the nanoparticles, enabling a PET scanner to track areas of tumor formation or the migration of cancer to different parts of the body. The PET approach will help oncologists spot suspicious areas earlier, he says.
“I’m an advocate of engineers teaming up with biomedical scientists to conduct interdisciplinary research,” he adds. “Engineers need to open their minds and be willing to solve problems in biology, while biologists should understand and appreciate the tools of engineering.” He points approvingly to the IEEE Circuits and System Society’s formation of the Life Science Applications and Systems Technical Committee, which organizes a workshop biannually with the U.S. National Institutes of Health to bring representatives from other IEEE societies to engage in dialogue with medical researchers on topics such as nanomedicine and man-machine interfaces. But for Chen, his work has just begun.
“My goal is to build a nanorobot which will travel through the bloodstream to monitor human health,” he says. “If diseases can be diagnosed earlier, most health problems can be better managed and treated more effectively.”