Chemical 'Paint' Helps Surgeons See Cancer's Borders

Removing all of the tumor is key to preventing recurrence, researchers say

MONDAY, July 16, 2007 (HealthDay News) -- Researchers say they've developed a tumor "paint" that illuminates cancerous cells and help surgeons spot the borders of tumors.

A team at Seattle Children's Hospital Research Institute and the Fred Hutchinson Cancer Research Center found that the paint -- a protein derived from scorpions called chlorotoxin -- helped surgeons distinguish between brain tumor cells and normal brain tissue during surgery.

"My greatest hope is that tumor paint will fundamentally improve cancer therapy. By allowing surgeons to see cancer that would be undetectable by other means, we can give our patients better outcomes," study senior author Dr. James M. Olson said in a prepared statement.

The findings are in the July 15 issue of the journal Cancer Research.

Chlorotoxin is linked to a molecular "beacon" called Cy5.5. The use of chlorotoxin:Cy5.5 improves the likelihood that surgeons will be able to remove all cancerous cells during surgery without damaging surrounding healthy tissue, the researchers said. This is especially important for brain cancer patients. About 80 percent of malignant cancers recur at the edges of sites where tumors have been surgically removed.

Until now, there has been no way to allow surgeons to "see" tumors during surgery.

The researchers also noted that current technology, such as MRI, can distinguish tumors from healthy tissue only if more than one million cancer cells are present. Chlorotoxin:Cy5.5 is able to identify tumors with as few as 200 cancer cells, which means that it's 500 times more sensitive than MRI.

The tumor paint has been successfully tested in mice, and pilot safety trials have been completed. The researchers are preparing required toxicity studies before they apply to the U.S. Food and Drug Administration for permission to begin human clinical trials with the tumor paint.

More information

The American Cancer Society has more about cancer surgery.

SOURCE: Children's Hospital and Regional Medical Center of Seattle, news release, July 15, 2007
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