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July 24, 2007

'Painting Tumors' Helps Surgeons In Removing Cancer Cells

Topics: Medicine

painting%20tumors.jpgWhen treating cancer with surgery, there's nothing as important as making sure that every last cancerous cell has been removed. Until recently, that hasn't been possible since cancer cells are often embedding within healthy tissue and can metastasize, spreading malignancies to other parts of the body.

Now, however, researchers at Seattle's Fred Hutchinson Cancer Research Center have come up with an innovative way of giving surgeons the upper hand against these wily cells. They've created a molecular "paint" that coats cancer cells so doctors can see the wayward cells that they may otherwise miss:

The paint is a blend of chlorotoxin derived from the scorpion (nonpoisonous to humans) and a fluorescent molecule that emits near infrared light. The scorpion-derived peptide homes in on the cancer cells and binds to them, bypassing healthy cells. The fluorescent tag is piggybacked onto the peptide. After doctors remove a tumor, they use a special camera that captures near infrared photons to look at the body and see any stray cells the scalpel left behind. At those wavelengths, light from the fluorescent marker cannot be blocked by blood, other body fluids or even thin bone.
Continue reading: Painting Tumors ...

The chlorotoxin used by the researchers is Chlorotoxin:Cy5.5, a molecular imaging bioconjugate composed of chlorotoxin (CTX) and Cy5.5. CTX is a 36 amino acid peptide with four disulfide bridges. The bioconjugate functions as a fluorescent molecular beacon that emits photons.

Not only will Cy5.5 reveal left-behind cells, it also helps surgeons avoid removing normal tissue. Cy5.5 begins binding to cancer cells within minutes, and the Cy5.5 signal lasts for 14 days. Importantly, Cy5.5 can identify tumors with fewer than 2000 cancer cells, making it 500 times more sensitive than MRI under operating conditions. The researchers believe that Chlorotoxin:Cy5.5 has the potential to be used in the future as a non-invasive screening tool for early detection of skin, cervical, esophageal, colon and lung cancers. It is also useful in identifying positive lymph nodes which could mean a significant advancement for breast, prostate and testicular cancers.

Related reading: Tumor Paint: A Chlorotoxin:Cy5.5 Bioconjugate for Intraoperative Visualization of Cancer Foci

Posted by Richard at July 24, 2007 7:51 AM



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