The humble Pap test, a screening test so good that American women now die of cervical cancer at only one-fifth the rate of 50 years ago, is one of the best tools in modern medicine.
Unlike mammograms, which detect breast cancers at an early stage, Pap tests spot abnormalities in cervical cells even before they become cancer.
In fact, if all women got Pap tests regularly, the incidence of cervical cancer — still the chief cause of cancer death in developing countries — could approach zero, specialists say.
Ironically, though, just as improvements are becoming available to make the Pap smear even better — by reducing the rate of both missed cancers and false alarms — cost-conscious health planners are wondering whether we can afford the new tests and even how often women should get Pap smears.
Cervical cancer is a sexually transmitted disease caused in virtually all cases by any one of four common papilloma viruses, which are spread primarily by genital skin contact. The major risks are having sex before age 20, having three or more sexual partners or having a history of abnormal Pap smears or genital warts. Smoking adds significantly to the risk because tobacco smoke bathes delicate cervical tissues in tar and nicotine.
Since the 1940s, when Dr. Georges Papanicolaou developed his now-famous method of scraping cells from the cervix, spreading them on a glass slide and examining them under a microsocope, the death rate from cervical cancer has plummeted, though it now seems to be rising again slightly in younger women. This year, it is expected to hit nearly 16,000 American women and kill nearly 5,000.
But those figures only begin to tell the story of what has become a $6 billion-a-year industry. Every year, American women have 55 million Pap smears — at $7 to $15 each — and four to five million of these are abnormal.
In most cases, the abnormal tests turn out to be nothing serious, says Dr. Ellen Sheets, director of the Pap smear evaluation center at Brigham and Women’s Hospital.
But in order to be sure, many women are sent into what doctors call secondary triage — more testing, usually with a $150 exam called colposcopy in which doctors use a high-powered microscope to look at the cervix. This is often followed by freezing, burning or using electrical wires to removesuspect tissue, at another $500 or more per patient.
All this is worth it, of course, if a woman leaves the doctor’s office 100 percent cured, as is usually the case when cervical abnormalities consist of mere dysplasia, the presence of abnormal cells, or carcinoma in situ, a noninvasive cancer.
But it can also be too much of a good thing.
Often, women whose Pap tests are only mildly abnormal “end up with a $500 procedure for a lesion that didn’t need to be treated in the first place,” says Dr. Michael Policar, former vice president of the PlannedParenthood Federation of America and now medical director of the Solano Partnership Health Plan, an HMO in Fairfield, Calif.
The problem, gynecologists say, is that Pap tests are nowhere near as accurate as women assume — or doctors would like.
Granted, things have improved since 1988, when Congress passed a law tightening lab practices following scandals over inaccurate tests read by overworked, underpaid technicians.
But even in good labs, human eyes still miss 20 percent or more of abnormal smears and, somewhat less frequently, tend to see abnormalities where none exist.
Because of this, researchers have been scrambling to fine-tune Pap testing with add-on technology, and a number of devices are now working their way through the US Food and Drug Administration approval process.
Several months ago, the FDA approved a system called PAPNET, which uses computers to re-read normal Pap smears already examined by human technicians. It’s not clear yet whether re-reading by computer “will be more helpful than human re-reading,” says Sheets of the Brigham.
Earlier this month, the FDA also approved for cervical screening a device developed by the Trylon Corp. in California, to be marketed soon by Pharmacia & Upjohn, Inc. in Michigan.
Called Pap Plus Speculosocopy, the device is a tiny light that is taped to a speculum, the standard device used to examine the cervix. After a Pap smear is done, the doctor simply swabs vinegar on the cervix and shines the blue- white light on it. Abnormal cells appear white, normal cells, dark.
The extra test adds $25 and five minutes to a Pap exam, but it can cut the rate of missed abnormalities to about 5 percent, says Dr. Steven Vasilev, director of gynecologic oncology at the City of Hope Medical Center in Duarte, Calif.
Vasilev, who has tested the device in hundreds of women, says “the returns are great, because you are decreasing the chance a patient will come back in two or three years” with cancer.
But many specialists are unconvinced the device will save enough lives to justify the cost. Dr. Diane Solomon, chief of the cytopathology section at the National Cancer Institute says, “I’m not convinced by the data I’ve seen so far.”
Neither is HMO medical director Policar, who says speculoscopy could be “a big deal” as a way to tell which women with abnormal Pap tests need expensive colposcopy. But as “the person who decides which tests to pay for and which not” in an HMO of 45,000 patients, he says he is not sure the test will prevent enough cases of cervical cancer to justify the extra cost.
Dr. Michele Follen Mitchell, director of colposcopy at M.D. Anderson Cancer Center in Houston, is also wary, though she has hopes for her own test, called fluorescence spectroscopy.
Down the line, other refinements may also help make Pap smears more accurate, including a machine to spread cells more uniformly on microscope slides and using infrared light and antibodies to spot abnormalities.
Even before such improvements become available, though, women should not hesitate to get Pap tests. Among all cancer detection tests, the standard Pap test is “probably the only true screening tool that has impacted the death rate,” says Sheets.
Even if doctors don’t know how often women should have it.
For years, the rule of thumb was a Pap test every year, and the AmericanCollege of Obstetricians and Gynecologists still recommends that for sexually active women.
If a woman doesn’t have a yearly Pap test, says Dr. Henry Klapholz, vice chairman of the obstetrics and gynecology department at Beth Israel Hospital, she may skip her annual pelvic exam, the main way of detecting ovarian cancer, as well.
But in 1988, a coalition of medical organizations changed Pap test guidelines. The guidelines say that “all women who are or have been sexually active, or who have reached age 18, should have an annual Pap smear and pelvic exam. After a woman has had three or more consecutive, satisfactory normal annual examinations, the procedure may be performed less frequently at the discretion of the woman and her doctor.”
Concerned about rising costs, “many insurers are pushing” for a three- year interval, says Sheets. In Europe, she adds, women get Pap smears every two or three years, yet have cervical cancer rates similar to those of American women, probably because they are less likely than Americans to skip scheduled exams.
“The real key,” says Cindy Pearson, program director for the National Women’s Health Network, is “to get tested regularly, at the very least every three years. This is the most preventable cancer we’ve got going