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Machine to help sort Pap smears

Laboratories that check Pap smears for signs of cervical cancer may soon become more automated: The Food and Drug Administration approved a computer system Tuesday that means some women will have their Pap tests checked solely by a machine instead of a person.

The goal is to allow NeoPath's AutoPap Primary Screening System to sort out the lowest-risk Paps so that lab workers will have more time to spend on the Pap smears most likely to show subtle signs of cancer.

"A lab that has a very high rate of accuracy is not going to see a great deal of improvement with the machine," said FDA device evaluation chief Susan Alpert. "A lab that has a lower rate of accuracy will get more benefit."

Some 60-million Pap smears are performed every year; the simple scrapings of the cervix can detect cancer and precancerous changes early enough to cure thousands. Pap smears have helped cervical cancer rates plummet. Still, an estimated 13,700 American women will get cervical cancer this year, and 4,900 will die.

The test isn't foolproof: Cytotechnologists must visually hunt tiny changes in hundreds of thousands of tiny cells. Between 3 percent and 25 percent of abnormal Pap smears are missed.

In 1995, the FDA approved two computer systems, including a first-generation AutoPap, to double-check Pap smears and help catch missed problems.

NeoPath wanted to go the next step and replace humans. It developed an improved AutoPap to set aside up to 25 percent of the Pap tests that look most normal. Lab workers would never see those.

Cytotechnologists would personally examine the remaining 75 percent of the tests.

Then, AutoPap would prompt a third check _ picking out 15 percent of the Pap smears most likely to be abnormal for a final exam.

A study of 25,000 Pap smears checked under standard lab practice and with the AutoPap-assisted method found the computer system helped labs catch 33 percent more suspicious cells, including two possible cancers that lab workers missed.

The machine also missed some problem Pap smears _ 11 of 4,800 that it designated low-risk _ but they were of the least suspicious type, Alpert said.

NeoPath of Redmond, Wash., said it will begin shipping the new AutoPap immediately.

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