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- THE WEEK, Page 30HEALTH & SCIENCEScalpel! Laser! Retrovirus!
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- An ingenious experiment offers hope for a new kind of surgery
- for cancer
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- One reason that brain cancer is so terrifying is that tumors
- tend to bury themselves deep in the gray matter, where scalpels
- and lasers cannot reach them without doing irreparable damage to
- the patient's mind. That is why scientists were particularly
- excited by an ingenious experiment reported last week in
- Science magazine. The procedure is a form of gene therapy, but
- it turns conventional molecular engineering on its head. Rather
- than trying to inject good genes into cells that lack their
- beneficial properties, scientists have found a way to put
- bull's-eyes on tumor cells in order to shoot them dead.
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- Making clever use of the fact that the familiar infectious
- agents called retroviruses will attack only cells that are in
- the process of dividing, researchers at the National Institutes
- of Health spliced a snippet of DNA from a herpes virus into one
- of these retroviruses and injected the combination into rats
- suffering from brain cancer. Since cancer cells are about the
- only cells that are dividing in a cancer-infected brain, the
- viruses were supposed to invade those cells and multiply. After
- five days, the rats were treated with an antiherpes drug. The
- hope was that the toxin would kill herpes-infected cancer cells
- and leave the rest of the brain alone.
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- "When I proposed this idea, people thought it was crazy,"
- says Kenneth Culver, an oncology researcher at the National
- Cancer Institute. But it worked like a charm. In 11 of the 14
- rats, the tumors disappeared completely. The results were so
- promising that an NIH watchdog committee has already okayed a
- similar test on humans. The risks are high. The researchers
- will, in effect, be putting mouse genes directly into human
- brains. But the payoff could be great. Scientists are now
- searching for other inoperable cancers that might succumb to
- what they are calling "molecular surgery."
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