Physics team lays groundwork for non-invasive tumour diagnosis technique

Oncologists may soon be able to quickly determine if certain tumours will resist chemotherapy thanks to work done by a UWindsor physics researcher and his graduate assistant.

The work, outlined in a paper published in the academic journal Physical Review E, describes a model created by PhD candidate Long Jian Liu and his academic supervisor Mordechay Schlesinger. That model mathematically illustrates how fluid pressure is distributed between cells inside a tumour, an essential measure used to determine whether chemotherapy will be effective.

“If the fluid pressure inside the tumour is too high, the chemotherapy won’t work,” explained Dr. Schlesinger, professor emeritus in the physics department, who also noted that elevated levels of interstitial fluid pressure can lead to the metastasis, or spread, of tumours.

Until now, doctors would need to insert a needle into a tumour in order to determine the pressure levels inside, Schlesinger said.

“It’s painful for the patient, and in some cases, you can’t even do it depending on the location of the tumour,” he added.

The model he helped develop, however, demonstrates in theory the relationship between pressure and fluid flow, and concludes that measuring a contrast agent as it flows away from the tumour may provide an accurate measure of both.

Schlesinger said that’s exactly what a group of scientists in Norway did at Oslo University Hospital’s Institute for Cancer Research. In a paper published in the academic journal Cancer Research, those scientists describe how they used a dye known as gadolinium diethylene-triamine penta-acetic acid (Gd-DTPA), injected it into mice with xenografts of several types of human cancer, and then used magnetic resonance imaging (MRI) to monitor fluid pressure and velocity. The experiment showed higher levels of pressure in the tumours of metastasis-positive mice than those whose cancer was not spreading.

The Oslo group’s findings were confirmed later in cervical cancer patients with pelvic lymph node metastasis, where they found the velocity of the fluid pressure flow to be higher than those without lymph node involvement.

The group – which cited Schlesinger’s team’s paper in their own article – said taken together, both experiments show that using Gd-DTPA in conjunction with MRI is an effective method for non-invasively visualizing tumour pressure. It also demonstrates the potential for using the technique as a new biomarker for tumour aggressiveness, they said.

Schlesinger said he’s delighted his team’s work could be used as the basis for such an important experiment.

“This is a great service to humanity,” he said. “We are all candidates for cancer. It can happen to each and every one of us.”

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