New Scan Tells Whether Cancer Treatment Is Working

From the WebMD Archives

Dec. 19, 2000 -- Before her death from a brain tumor, a 13-year-old girl let researchers take a new kind of picture of her disease. Had doctors known then what they are beginning to learn now, the resulting images might have saved her life -- just as they promise to save the lives of future cancer patients.

Even as the girl bravely endured seven months of chemotherapy, the images showed that water had begun to move less freely in the area of the tumor. Later, when standard tests showed the drugs hadn't worked, doctors switched to a different drug regimen in a doomed effort to save her. Soon after the switch, water in the tumor area began to move more freely.

What this meant was unclear at the time. But now that more is known about the new imaging technique, it is possible to see that the drugs tried at first were not working. If her doctors had known this in time to make a change, the second drug regimen likely would have been more successful.

"This girl was a trooper," University of Michigan researcher Brian D. Ross, PhD, tells WebMD. "What's really amazing is that we see the [effect of treatment] dropping -- all that time she was receiving [the first] chemotherapy, the [effect of treatment] was going down. But when they gave her the [second] therapy -- by then she was on her deathbed -- the [effect of treatment] changed and went up. When it was going down [at the beginning, we now know] they should have stopped treatment and switched to the other therapy. When she died, the tumor was enormous." Ross co-authored a study of this new imaging technique that tested its usefulness in animals.

The new test uses a high-tech machine that has now become standard in most hospitals -- a magnetic resonance imaging (MRI) device. By getting new information -- called diffusion MRI -- Ross and co-workers can tell how easily and quickly water moves across extremely tiny distances. Living cancer cells have unbroken membranes around them that slow water flow. But when therapy kills these tumor cells, their membranes break down and water flows through them more easily.

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Getting the new information would add only a few seconds to standard tests -- and could provide information that normally takes several months to learn.

"We think within a week or so you could tell whether a cancer therapy is working -- that is our hope," says Ross, whose study is published in the Dec. 20 issue of the Journal of the National Cancer Institute. "Well before the toxicity of chemotherapy or radiation therapy kicks in -- before your hair is falling out and before you have nausea -- you could switch to a more effective drug."

Robert J. Gillies, PhD, a professor of biochemistry at the University of Arizona, is also studying the diffusion MRI technique. "In animals, it works great," he says. "In humans, we are cautiously optimistic -- we haven't done enough patients yet. We have studied five patients with recurring ... breast cancer [that had spread] to the liver. The data are very promising."

Ross and Gillies soon plan to begin a large-scale trial to validate the test for several different types of cancer. Ross estimates that if all goes well, doctors may begin using the test within six months to two years.

WebMD Health News Reviewed by Jacqueline Brooks, MBBCH, MRCPsych
© 2000 WebMD, Inc. All rights reserved.

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