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New Technique Helps Treat Tumors

Short bursts of intense ultrasound boost power of gene therapy to fight malignancies

TUESDAY, April 26, 2005 (HealthDay News) -- The use of short pulses of high-intensity focused ultrasound (HIFU) shows promise as a way to enhance gene therapy treatment of cancer without destroying healthy tissue, says a study by researchers at the National Institutes of Health.

Long and continuous exposures of HIFU, which is more powerful than normal ultrasound, can destroy tumors by raising the temperature inside cancerous cells. This study found that pulsed HIFU makes tissues permeable and better able to take in genes and other therapeutic agents injected into the body.

"Basically, we're using sound waves to open up the tissue by producing gaps between the cells, making it leakier and more prone to taking up various genes, agents and compounds," Victor Frenkel, a staff scientist in the diagnostic radiology department at the NIH Clinical Center, said in a prepared statement.

The researchers used pulsed-HIFU on tumors in mice and then injected them with a reporter gene that could be easily measured in the bodies of the mice. The reporter gene was visible in all sections of tumors exposed to pulsed-HIFU, but was barely detectable in tumors not targeted with pulsed-HIFU.

When they conducted an analysis, the researchers found that reporter gene levels were nine times higher in the tumors targeted by pulsed-HIFU than in the non-targeted tumors.

"This procedure is hypothetically generic for enhancing delivery to all tissues. Previous studies ... have shown that pulsed-HIFU increases the uptake of drugs. Now we've shown that it works for genes, and we're making the case that there's a connection between the two," Frenkel said.

The findings are published in the May issue of the journal Radiology.

More information

The U.S. National Cancer Institute has more about gene therapy for cancer.

SOURCE: Radiological Society of North America, news release, April 26, 2005
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