To Detect Cervical Cancer, Pap Smear Still is the Best Test

This article was first published in the Poughkeepsie Journal on Sunday, June 3, 2007.

To Detect Cervical Cancer, Pap Smear Still is the Best Test

Without fail for almost 20 years, Darlene Fehlhaber of Glendale, Ariz., has subjected herself to something she'd just as soon skip: an annual Pap test.

"I know it's worthwhile," she said, "but it's not the best way to start your day."

Like millions of American women, she views her screening for cervical cancer as a ritual she wouldn't miss, even while she looks forward to the day she can cross it off her must-do list.

Don't jump out of those stirrups too quickly, though.

Amid hoopla about a new vaccine to prevent cervical cancer, health-care professionals are urging women not to abandon the powerful, if imperfect, Pap.

"Cervical cancer is one of the most completely preventable cancers there is," Phoenix physician Lurlyn Pero said. "It's a very slow-growing cancer, so we're counting not just on the reliability of the Pap smear to find abnormal cells early enough to eliminate them, but on the reliability of the patient getting in here and doing it once a year."

Pre-cancerous lesions and small cancers of the cervix can be removed surgically. In more serious cases, the disease is treated with surgery, chemotherapy and radiation.

So what is a pap test?

In 1945, about five years before Cornell University physician George Papanicolaou's screening began to catch on, about 23 of every 100,000 American women developed cervical cancer and 14 of 100,000 died, said obstetrician-gynecologist Alan Waxman of the University of New Mexico in Albuquerque.

Those numbers dropped to about nine out of 100,000 for incidence and three out of 100,000 for mortality by 1990.

Traditionally, a doctor or other health-care worker scrapes cells from a woman's cervix, smears them on a microscope slide and sends the slide to a lab for evaluation.

In the newer liquid-based Pap, used for about 80 percent of tests in the U.S., the scraped cells are placed in a vial of preservative, sent to a lab and spread evenly on a slide for study.

If the lab finds abnormal cells, it can use liquid left from the Pap test to do a "reflex" human papillomavirus (HPV) genetic test, which was approved by the FDA in 2000 for confirming results. It looks for the DNA of 13 of the HPV strains that cause cancer.

"You get better quality cells (with the liquid test)," Pero said. "You get cells that are transported in a healthy fashion. And if the reflex test is positive for HPV, then you know the abnormalities seen in the Pap smear are probably reliable."

Vaccine announced

The Gardasil vaccine, from Merck, is not the complete solution in the fight against cervical cancer. The vaccine was approved by the Food and Drug Administration in 2006 for females ages 9 through 26. It helps protect against infections of human papillomavirus types 16 and 18, which cause about 70 percent of cervical cancer, and HPV types 6 and 11, which cause about 90 percent of genital warts.

The vaccine doesn't help women who were infected before immunization, nor does it guard against the more than 30 other types of genital HPV, the most common sexually transmitted infection in the United States, Pero says.

All this guarantees a role for the Pap smear - although in an updated version and on a slightly different timetable in some cases - "for a long time into the future," Waxman said.

"I think (the vaccine) is going to make a huge impact," he said, "but we're not going to feel the full force for another 20 years. The public health impact will be in young women who have not become sexually active."

Cancer rates plunge

Waxman, an expert in Pap tests and cervical cancer, is co-author of Pap screening guidelines from the American College of Obstetricians and Gynecologists.

He said the simple test has brought about dramatic drops in cervical cancer rates.

"This now is a disease that most gynecologists never see," he said.

This year, the American Cancer Society predicts, about 11,150 new cases of invasive cervical cancer (the equivalent of about 7.6 per 100,000 women) will be diagnosed in the U.S., and about 3,670 women (about 2.5 per 100,000) will die.

Of those who get the disease, Waxman said, about half have never had a Pap test, 10 percent haven't had one in the past five years and another 10 percent haven't followed up on abnormal test results.

Worldwide, cervical cancer is the second-most-common cancer, with more than 470,000 new cases and 233,000 deaths each year, the Centers for Disease Control and Prevention says.

Studies have shown that a Pap provides reliable results 51 to 80 percent of the time, Waxman said, but a single inaccurate reading usually isn't a problem for a woman screened regularly. It can take years for a pre-cancerous lesion to develop into cancer, and what's missed in one smear can be caught in the next.

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