New Pap guidelines reduce screening, but raise concerns about compliance
By Bonnie Darves
Women everywhere will likely view new guidelines that call for less cervical cancer screening for certain women as good news. But some in the oncology community are worried about the fallout on patients' attitudes toward—and compliance with—regular Pap testing.
Earlier this winter, the U.S. Preventive Services Task Force (USPSTF) and the American Cancer Society (ASC) each issued new guidelines for cervical cancer screening. While many aspects of the guidelines did not change, both organizations revised key recommendations about when physicians should begin screening women—and when they can safely discontinue.
The guidelines now recommend that physicians start screening patients for cervical cancer approximately three years after the onset of sexual activity, or at age 21. They also suggest screening women over 30 with a history of normal results every two to three years. Finally, they say that for older women who have little risk of developing cervical cancer, physicians can stop screening altogether.
Both organizations also took an ambivalent stance toward new screening technologies like the liquid-based "Thin-Prep" test and the human papillomavirus DNA test as a primary screening test for cervical cancer. (For more details about the guidelines, see "An overview of the new guidelines on Pap smears.")
In calling for a two- to three-year screening interval, researchers cite evidence that cervical cancer grows slowly and doesn't necessarily need to be detected immediately. Data also show that aggressively testing for cervical cancer can result in unnecessary biopsies and procedures.
Those same researchers, however, are quick to point out that Pap testing is one of public health's biggest success stories, and they worry that the new guidelines will lead many patients to take the need for regular gynecologic visits less seriously. As a result, they say physicians could find themselves in the difficult position of trying to convince patients that they still need an annual visit to the doctor.
When can you stop screening?
The new USPSTF guidelines say physicians can stop screening low-risk women at age 65, while the more conservative ACS guidelines recommend screening low-risk patients through age 70. Both groups, however, note that the choice of 65 or 70 is somewhat arbitrary.
Because previous guidelines never gave physicians an age at which they could safely discontinue screening, many doctors now face a decision they have not had to make before.
Debbie Saslow, PhD, director of breast and gynecologic cancer for the ACS and chief author of the new guidelines, said that new evidence is driving the revised recommendations. "Yes, there are data that show older women do get cervical cancer," she said. "But we know now that they tend to be women who haven't been screened, or women who haven't been screened for 10 to 20 years."
That's why both sets of guidelines say older women who have been screened regularly with normal results may decide they don't need to continue getting Pap smears.
Both women and their physicians will welcome this new thinking, Dr. Saslow said, because obtaining an adequate sample for testing becomes more difficult as women age. Atrophying tissue not only makes the procedure technically more difficult, but also increases the chance of unnecessary follow-up tests.
How do you decide when it's safe to discontinue Pap smears for your older patients? The guidelines advise physicians to take into account previous Pap results.
Both the ACS and USPSTF guidelines say that women who have certain risk factors for cervical cancer—such as HIV or a history of high-grade lesions—should continue regular screening. (The ACS advises physicians to continue screening women over age 70 if they have a previous history of cervical cancer or have HIV.)
Younger women and overtreatment
Both guidelines also reiterate that annual screening may be unnecessary for many women over age 30.
"The risk factors [for cervical cancer] vary based on a number of issues, and these new guidelines attempt to take them into account," said medical oncologist Mary A. Simmonds, FACP, national volunteer president of the ACS and clinical professor of medicine at Penn State University College of Medicine in Hershey, Pa. "With this change, physicians may have to provide patients a quick explanation about why some women are more at risk than others for this particular cancer, and why screening [recommendations] aren't cut and dried."
Most young and middle-aged women who have had two or three consecutive normal Pap smears can safely move to a screening interval of three years, Dr. Simmonds said. However, she said, you may want to continue more regular screening for patients who have HIV or whose mothers took the drug diethylstilbestrol (DES). The drug, used between 1947 and 1971 to prevent miscarriages, has been associated with vaginal and other cancers.
'We now know that cervical cancer is not like other cancers, where it's important to identify and treat it as soon as possible.'—Debbie Saslow, PhD
"Once women have had normal Pap smears for two to three years, there doesn't seem to be any yield in doing it every year, particularly in terms of cost benefit," explained Janet Allan, PhD, RN, NP, vice chair of the USPSTF. "But obviously if something has changed in a woman's life, the screening interval should change. There has to be some kind of negotiation between the patient and clinician."
Researchers are calling for more flexibility in screening intervals because of a growing body of data on the nature of cervical dysplasia. Recent studies show that young women who become infected with human papillomavirus (HPV)—now known to be the leading cause of most, if not all, cervical cancer—may develop low-grade lesions that do not progress to cancer.
In fact, HPV infections appear to progress to cancer extremely slowly. Research has shown that high-grade lesions tend to develop after three to five years, and that lesions become full-blown cancer after 10 to 20 years.
"We now know that cervical cancer is not like other cancers, where it's important to identify and treat it as soon as possible," Dr. Saslow said.
In younger women, a large percentage of low-grade lesions will resolve on their own. However, when these lesions show up on Pap smears, physicians often order invasive tests like a biopsy or colposcopy. Drs. Saslow and Simmonds both said that researchers now believe such ablative procedures—which can constitute overtreatment in some cases—might contribute to infertility and should be avoided unless the situation truly merits further testing.
Paula Hillard, MD, a member of the task force and professor of obstetrics and gynecology at the University of Cincinnati, said that overtreatment of young women has been a concern that the new guidelines attempt to address. Dr. Hillard noted that 50% of sexually active adolescent girls have been exposed to HPV and that their Pap tests will show mild abnormalities. (Some studies go even farther and say that more than 70% have been exposed.) But that doesn't necessarily mean they warrant further testing.
"The vast majority of adolescents with abnormal Pap results have low-grade lesions," she said. "Although the guidelines suggest only observation, many girls end up having ablative treatment because the [abnormal] findings kick off a process of biopsy and other treatments that have some potential for harm."
The big picture
Even as public health experts suggest less screening for some women, they are quick to emphasize that Pap test screening has proven an important, if little noted, success story in American medicine.
Mortality from cervical cancer in the United States has decreased more than 70% over the last five decades. The disease, once the leading cause of cancer deaths in women, now ranks 13th.
In 1973, there were 14 new cases of cervical cancer for every 100,000 American women. By 1994, that number had dropped to 7.8, largely as a result of better screening, Dr. Allan said.
While public health experts attribute much of that success to stepped-up screening strategies, they note that medicine can do better. Of the 13,000 new cervical cancer cases diagnosed each year in this country, more than half occur in women who either have never been screened or weren't screened in the previous five years.
"We could greatly reduce cervical cancer incidence and mortality by increasing screening among women who've been screened irregularly or have never had a Pap smear," said Dr. Simmonds. She recited another sobering statistic: While 92% of women survive cervical cancer when it is detected early, about 4,100 American women still die from the disease each year.
Physicians' greatest challenge may be figuring out how to balance the guidelines' recommendations with those grim statistics. How do you get the patients who can really benefit from cervical cancer screening to keep coming in for testing and other care?
"This will affect how internists deal with their female patients, because in a sense, the guidelines complicate discussions about screening," Dr. Hillard said.
She recommended that physicians state the case simply, telling patients that the medical community has changed its thinking about certain screening issues. That's because more is known now about the rate at which cervical cancer progresses—and because the majority of mild changes discovered with Pap tests go away.
Physicians should encourage female patients to go for annual check-ups, even if they don't need annual Pap tests.
Although Pap test screening every two to three years has been recommended since 1987, many women and their doctors still equate an annual trip to the doctor with a Pap test. These women may be delighted to learn that they don't need annual screening, but they may need a firm reminder that the yearly checkup is still important.
"Not all women recognize the other benefits of the annual visit, such as blood pressure screening and discussions about weight or other health risk issues," Dr. Hillard said. "So the physician's message about the new guidelines should be, 'You still need that annual visit.'"
Bonnie Darves is a freelance writer in Lake Oswego, Ore.
The information included herein should never be used as a substitute for clinical judgment and does not represent an official position of ACP.
New cervical cancer screening guidelines issued by the U.S. Preventive Services Task Force (USPSTF) and the American Cancer Society (ACS) are noteworthy because they call for less screening of adolescents, older women and women who have had a hysterectomy. They also address the role of new and emerging testing technologies.
Here is a summary of major changes in both guidelines:
Starting screening. Both guidelines say that screening with cervical cytology should begin within three years of the onset of sexual activity or at age 21, whichever comes first. Previous guidelines recommended starting screening at age 18, or at the onset of sexual activity.
Screening intervals. Once you have begun screening, test women annually until age 30. If results are normal for two to three years in a row and the patient has no new risk factors, you can screen every two to three years thereafter. (The ACS recommends screening annually until age 30 if you perform a conventional Pap smear or every two years if you use a liquid-based Pap test.)
Post-hysterectomy patients. Both sets of guidelines say you should not continue to screen women who have had a total hysterectomy for benign conditions. However, you should continue screening the small number of women—less than 1%—who retain their cervix after undergoing a hysterectomy.
Ending screening. Both guidelines recommend against routinely screening women after age 65 to 70 if they have received regular screening with normal results three times in a row. Continue screening patients over 65 who have other risks for cervical cancer (such as HIV or immune system disorders) or a history of high-grade lesions.
New technologies. The two guidelines offer different recommendations on emerging screening methods. The ACS recommends using either the new liquid-based Pap (LBP) or a conventional Pap smear, but it cites the improved sensitivity of the newer test and discourages physicians from using the LBP too frequently.
However, the task force guidelines conclude that evidence was insufficient to recommend for or against routinely using new technologies, including LBP, as substitutes for conventional Pap smears.
Studies show the LBP produces slightly higher rates of false positives. That concerned some experts involved in developing the guidelines, because false positives may prompt further testing that proves unnecessary. Other review panels, however, were not concerned, citing the fact that false positive rates go down as proficiency improves—and that the LBP's greater sensitivity outweighs its downsides.
Both guidelines reviewed several other emerging technologies, including computer-aided visualization, computer-assisted screening and optical-probe devices. Neither organization issued specific recommendations on these technologies because of the lack of FDA approval or insufficient data.
Routine HPV testing. Neither guideline fully recommended using human papillomavirus (HPV) DNA testing as a primary screen for cervical cancer, in part because the test is awaiting FDA approval.
The task force concluded that evidence was insufficient to recommend for or against HPV testing as a primary screening method, or as an adjunct to regular Pap tests. It did note, however, that clinical trials now underway may soon clarify the test's role in cervical cancer screening.
The ACS guidelines take a similar stance. The review panel declared the technology promising and suggested that once HPV DNA testing is approved, it might be an appropriate addition to cervical cytology testing for women age 30 and older, as long as it is not done more frequently than every three years.
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