For decades, women have been told that they should visit their gynecologist every year for a test to screen for cancer of the cervix. And compliance has been associated with dramatic resultsbetween 1955 and 1992, cervical cancer rates decreased 74%, largely as a result of increased use of the Pap smear. Today, cervical cancer is most often diagnosed in women who were never, or rarely, screened.
Now, in separate sets of guidelines recently issued by the American Cancer Society (ACS) and the U. S. Preventive Services Task Force (USPSTF), researchers are forcibly backing away from the notion that every woman needs an annual screening test. Both groups had previously recommended less frequent screenings, but that suggestion was largely ignored by gynecologists.
This time around, ACS and USPSTF are strengthening their stand that fewer annual tests are needed, and they are going even further. They now recommend that women start screening at a later age, 3 years after onset of sexual activity (or age 21, whichever is earlier), and stop screening altogether at age 65 or 70, or earlier if a woman has had a complete hysterectomy with removal of the cervix. Previous guidelines had called for screening to start at onset of sexual activity, or age 18, and continue indefinitely, even if a woman had no cervix.
The changes reflect a refined understanding that, although the human papillomavirus (HPV) causes cervical cancer, its presence in younger women is often harmless. Researchers now say that the harms of continued annual screening, such as false-positive tests and invasive procedures, may outweigh the benefits of annual screening.
With sophisticated technologies, such as liquid-based Pap tests, and a new test for HPV that the U.S. Food and Drug Administration is now considering for approval, it is critical that women not be screened too frequently, says Debbie Saslow, Ph.D., director of breast and cervical cancer control at the American Cancer Society. These tests are more sensitive and potentially less specific, which can result in a positive result for a virus that will eventually just go away, as most of these infections do, she said.
"We know women are being overdiagnosed and overtreated," Saslow said. "Some doctors are being very aggressive with positive results of slightly abnormal and low-grade lesions from the test, ordering multiple biopsies which sometimes results in fertility and pregnancy problems."
But problems with overdiagnosis will still exist for women who continue to use their appointment for a Pap smear as their annual health care visita practice many gynecologists go along with, said Kenneth Noller, M.D., professor and chair of the Department of Obstetrics and Gynecology at Tufts University-New England Medical Center, Boston. "If they dont come in for annual screening, they wont get the blood pressure tests and other screenings that they need," said Noller, who worked with the ACS on its guidelines as a representative from the American College of Obstetricians and Gynecologists (ACOG).
Noller said that ACOG has suggested its member physicians cut back on screenings, and "many physicians do report that they do discuss screening less frequently with their patients, but it varies a lot from practice to practice." Little by little the message to screen less frequently is getting out, but it is going to require some work to make sure the word spreads farther."
Although the recommendations issued by ACS and USPSTF differ in some important details, they are similar enough that in late January, the National Cancer Institute issued a statement supporting both sets of guidelines. "The big story is that there is so much agreement between the two groups in their recommendations," said Diane Solomon, M.D., medical officer with the NCI Division of Cancer Prevention Breast and Gynecologic Cancer Research Group.
For example, both groups say that, because many young women have transient and harmless HPV infections, screening should begin 3 years after sexual activity begins, or age 21, whichever comes first. "In that younger age range, there is a high prevalence of HPV infection, and abnormal Pap tests elicit a whole lot of follow-up, but these women are at exceedingly low risk of cervical cancer," Solomon said.
Although ACOGs Noller agrees with the age recommendation, he said his organization is concerned that women who are sexually active well before age 21 may not be screened until that age. ACOG intends to draft its own guidelines soon, he said.
The two groups also agree that women can stop screening when they are older, but differ on the age: ACS says after age 70 and USPSTF says 65, if patients have a history of normal results.
The groups say less frequent screening is important, but each group defines that differently. The ACS guidelines state that women should have a regular Pap test every year, or a liquid-based Pap test every 2 years, until age 30. Then, if they have had three normal test results in a row, they can be screened every 2 or 3 years. The task force, however, says there is no need to wait until age 30 to cut down on screenings. It recommends screening at least every 3 years in women of any age who have had at least two normal annual screenings.
"We found no direct evidence that annual screening achieves better outcomes than screening every 3 years," said the task force chair Alfred Berg, M.D., Ph.D., professor and chair of the Department of Family Medicine at the University of Washington, Seattle. "We are thinking along the same lines, but ACS is more reluctant to cut back on normal screening."
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"We are not making value judgments against HPV testing or liquid-based cytology," said Berg. "We just found insufficient scientific information to recommend them." Saslow, of the ACS, said the disparity between the groups comes from the "different processes used by each organization, and their different missions."
But Saslow, Berg, Solomon, and Noller all agree that it is important for their organizations to, perhaps for the first time, minimize the differences between the guidelines in regard to cervical cancer screening, and stress the similarities between them. Added Berg, "This is a popular subject for recommendations."
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