What's Going On With Cervical Cancer Screening in US?
Gerald Hurowitz, M.D.·Published 7 January 2013·11 min read
Key points
In their report on cervical cancer screening released yesterday, the Centers for Disease Control and Prevention (CDC) startlingly estimated that 22 million women in the United States may have undergone such screening unnecessarily, because they had already had hysterectomies.
The screening interval is the time between the screening tests.
Harper emphasized that the data are based on self-reporting, and thus are subject to bias.
Commenting specifically about the data on Pap tests done after hysterectomy, Dr.
In their report on cervical cancer screening released yesterday, the Centers for Disease Control and Prevention (CDC) startlingly estimated that 22 million women in the United States may have undergone such screening unnecessarily, because they had already had hysterectomies.
An expert approached by Medscape Medical News to comment on the issue cautioned that the data collected by the CDC were from women self-reporting and so may be subject to bias. She also suggested that some of the unnecessary testing, which is contrary to guidelines that have been in place for a decade, may be due to confusion stirred up by educational campaigns for the human papilloma virus vaccine Gardasil (Merck & Co).
The CDC analyzed data collected from 2000-2010 by the Behavioral Risk Factor Surveillance System on screening for cervical cancer using the Papanicolaou (Pap) test.
In one of the articles published in Morbidity and Mortality Weekly Report, the CDC highlighted the fact that during the study period, screening in women after a hysterectomy had declined from 73.3% in 2000 to 58.7% in 2010.
But this means that more than one half of the women were undergoing Pap tests unnecessarily, because hysterectomy involves removal of the cervix in the majority of cases (94% of cases, the CDC estimates).
Such women do not need cervical cancer screening - and it has been specifically discouraged in guidelines from all the major organizations since 2002-2003.
Several media reports highlighted this finding and emphasized the huge waste of financial resources this involves.
Who has screening? If you are between the ages of 25 and 60 in the UK, the NHS cervical screening programme will contact you every 3 to 5 years and ask you to go for a cervical screening test. The exact age groups for screening vary between the different countries of the United Kingdom.
In England and Northern Ireland, women between 25 and 64 years are screened.
In Scotland, women between 20 and 60 are invited for screening.
In Wales, women between 20 and 64 are screened.
Why the screening interval varies
The screening interval is the time between the screening tests. This used to vary between health authorities. But research reported in 2003 by Cancer Research UK showed that the screening interval should be decided by age. We can pick up the most cancers by screening women every 3 years if they are 25 to 49 years old and every 5 years if they are between 50 and 64.
For women between 25 and 49, 3 yearly screening prevents 84 cervical cancers out of every 100 that would develop without screening. 5 yearly screening will only prevent 73 cancers out of 100. So the guidelines now recommend screening women 3 yearly if they are under 50.
Written and revised by
Gerald Hurowitz, M.D.
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It is acceptable and safe for women of 50 or more to have 5 yearly smears. Screening 3 yearly doesn't give any extra protection for this age group. This is probably because abnormal cells develop more slowly in women over 49.
The NHS in England and Northern Ireland have adopted these recommendations. So if you are between 25 and 49 and live in England or Northern Ireland, your health authority will offer you 3 yearly cervical screening.
The CDC itself commented that in this population, any benefit from screening "might be outweighed by the net harm." Such harm may include false-positive tests leading to needless patient anxiety and invasive procedures.
"The false-positive rate...is indeed a great potential harm to women and cost to the healthcare system," says Diane Harper, MD, MPH, professor of community and family medicine/obstetrics and gynecology at Dartmouth Medical School, in Hanover, New Hampshire, and director of the Gynecologic Cancer Prevention Research Group at the Norris Cotton Cancer Center.
Medscape Medical News approached Dr. Harper to shed some light on some of the findings from the survey.
Self-Report Data Are Subject to Bias
Dr. Harper emphasized that the data are based on self-reporting, and thus are subject to bias.
"We have ample evidence to show that women of all ages are not cognizant of what a Pap test is," Dr. Harper said. "Most women believe that anytime they have an examination of the pelvic area, whether a speculum was used or not, they had a Pap test."
This has been shown in multiple research studies, and it raises questions concerning the validity of the self-report nature of the CDC survey, she said. "Hence, what is really being compared is whether women's perceptions of having had a Pap test have changed with the new guidelines."
"The second issue with the CDC survey data," she continued, "is that the answers women can choose for frequency of Pap testing are hard for women to internalize. Most women can distinguish 'never' from 'ever. ' And most women can distinguish within the past 12 months/year. But at frequencies longer than a year, there is very poor recall accuracy, leading to tremendous bias how the data are interpreted."
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Merck Education Created Confusion
Commenting specifically about the data on Pap tests done after hysterectomy, Dr. Harper puts some blame onto the Merck advertising/educational campaigns for Gardasil, which emphasize how human papilloma virus (HPV) is related to vaginal, vulvar, anal, and cervical cancers. These campaigns have "left most of the population and many ob/gyn as well as primary care doctors very confused about how to detect these increasingly more common HPV-related cancers," she told Medscape Medical News.
"It does not surprise me that physicians have taken a woman's risk for HPV exposure (number of sexual partners or past HPV infection) and stated that even with a hysterectomy for reasons other than HPV, there is no other way than a Pap test to determine if a vaginal cancer is beginning. There are a number of incorrect assumptions in that line of thinking, but that line of thinking has been spawned after the intense advertising campaign Merck undertook for their HPV vaccine," she said.
In its report, the CDC also mentions vaginal cancer as a reason cited by proponents of continued screening after hysterectomy. "However, vaginal cancer is rare, and the value of cytology tests to detect vaginal cancer in the absence of a cervix is unknown," the agency points out.
Unnecessary Testing in Other Groups
The CDC survey also highlighted several other groups of women who are undergoing cervical cancer screening unnecessarily and contrary to guidelines.
What to do if you are under 25 or over 64 The original cervical cancer screening programmes across the UK screened women from 20 to 64. The screening programme in England and Northern Ireland now starts at 25 because cervical cancer is very rare before this age. But changes in the cervix are quite common in younger women. So screening younger women can lead to unnecessary treatment and worry.
There is still more evidence coming in about the exact age groups we should screen. Wales and Scotland are still screening from age 20 until more evidence comes in, including from their own screening programmes. Another complication is that liquid based cytology has been introduced over the last few years. If you make more than one major change at a time to any health programme, you won't necessarily know which change is responsible for improvements in your service. In Wales, for example, they decided to stick with the original screening age, and introduce LBC fully before making any more changes.
Make sure that you begin having regular cervical screening as soon as you are 25 if you are sexually active. If you are under 25 and are at all concerned, talk to your GP or go to a well woman clinic.
In England, Wales and Northern Ireland, the screening programme stops at 64. This is because women who have had normal cervical screening tests are very unlikely to go on to develop cervical cancer after this age. The NHS guidelines say that if your last 3 cervical screening tests were normal when you are 64, there is no need to have any more. But many older women have not had enough tests. The UK cervical screening programme has not cut the number of cases of cervical cancer as quickly as it hoped. One reason for this is because many older women have never had tests.
So, if you are over 64 and your last 3 tests were normal, you will not be asked to go to have any more. If you are over 64 and have had abnormal tests, you will continue to be invited for regular tests in the normal way. In Scotland, the screening programme stops at 60.
If you have never had a cervical screening test, you should have one done regardless of your age unless you have never been sexually active. Ask at your GP surgery or well woman clinic.
Remember that if you are over 64 and have not had 3 normal tests in a row, you should carry on having regular tests until you do. Make sure you ask at your GP or well woman clinic if you think you should continue to have regular screening tests.
Although there had been some variation in recommendations made by different organizations in the past, updated guidelines released last year saw a convergence of opinions and very similar recommendations issued by the American Cancer Society, the American College of Obstetricians and Gynecologists, and the US Preventive Services Task Force.
In the new guidelines, there were specific recommendations that cervical cancer screening should begin at age 21 years, and not before, and yet data from the CDC survey suggest that Pap testing is being carried out in 18- to 21-year-olds.
That may not be the case. Dr. Harper explained that what these young 18- to 21-year-old women were reporting as a Pap test may actually have been a test for chlamydia, "which is prime in this age group."
Although it can be tested via urine, a chlamydia test is often done via a cervical sampling (ie, by a pelvic examination with a speculum), she explained. "Hence, a woman 18 to 21 who was being screened for chlamydia may have reported that she also had a Pap test done, not really knowing whether she did or not. Most of the time, the nurse practitioners or physicians who do the sample collection only report back that the results are 'normal' and not specifically that a chlamydia test was negative and a cytology test showed no abnormal cells."
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"The other 'quiet' reason is that the incidence of cervical cancer in the US in women under the age of 21 is 1.7/100,000. This is a real number, and this means that real young women get cervical cancer, and some of them die," Dr. Harper added.
"However, cytology is only good enough to reduce cervical cancer to 2.8/100,000, so getting Pap testing does not allow us to detect this small but real number of young women with cervical cancer. Adding HPV testing to cytology in this age group just creates a very large number of false positives. Hence, the reality is that we have no perfect system - Gardasil can only reduce the cervical cancer rate to 14/100,000, which is worse than Pap screening and not a way to protect all of the 1.7/100,000 young adolescents from cervical cancer. Hence, we accept that some cervical cancers will not be detected," she said.
Practice Changes Take Time
Another finding from the CDC survey was data suggesting that women in the 22- to 30-year-old age group were undergoing Pap tests annually instead of every 3 years, as per the new, updated guidelines.
This as well as some of the other findings suggest that it is taking some time for recommendations in the guidelines to filter through to clinical practice. Dr. Harper offers a few suggestions as to why this is the case: physicians may not be understanding the evidence for the change in the screening recommendations; reimbursement for the test still occurs; the patient feels at risk and requests frequent testing ("or the same testing as my sisters had..."); and nursing staff may set up the clinic rooms not understanding or accepting the change in guidelines.
The American Cancer Society at March 14, 2012 released new screening recommendations for the prevention and early detection of cervical cancer. Screenings are tests for women who have no symptoms of cervical cancer. Among the changes: the American Cancer Society no longer recommends that women get a Pap test every year.
During the past few decades, screening has reduced deaths from cervical cancer, as doctors have been able to find cancer early and treat it, or prevent it from ever developing. Researchers continue to find out more about what causes cervical cancer, and the best ways to screen for it.
There are 2 types of tests used for cervical cancer screening.
The Pap test can find early cell changes and treat them before they become cancer. The Pap test can also find cervical cancer early, when it's easier to treat.
The HPV (human papilloma virus) test finds certain infections that can lead to cell changes and cancer. HPV infections are very common, and most go away by themselves and don't cause these problems. The HPV test may be used along with a Pap test, or to help doctors decide how to treat women who have an abnormal Pap test.
The American Cancer Society regularly reviews the science and updates screening recommendations when new evidence suggests that a change may be needed. The latest recommendations are:
All women should begin cervical cancer screening at age 21.
Women between the ages of 21 and 29 should have a Pap test every 3 years. They should not be tested for HPV unless it is needed after an abnormal Pap test result.
Women between the ages of 30 and 65 should have both a Pap test and an HPV test every 5 years. This is the preferred approach, but it is also OK to have a Pap test alone every 3 years.
Women over age 65 who have had regular screenings with normal results should not be screened for cervical cancer. Women who have been diagnosed with cervical pre-cancer should continue to be screened.
Women who have had their uterus and cervix removed in a hysterectomy and have no history of cervical cancer or pre-cancer should not be screened.
Women who have had the HPV vaccine should still follow the screening recommendations for their age group.
Women who are at high risk for cervical cancer may need to be screened more often. Women at high risk might include those with HIV infection, organ transplant, or exposure to the drug DES. They should talk with their doctor or nurse.
In short, the American Cancer Society no longer recommends that women get a Pap test every year, because it generally takes much longer than that, 10 to 20 years, for cervical cancer to develop and overly frequent screening could lead to procedures that are not needed.
"All past analyses have shown that it takes about 10 years for physician behaviors to change to reflect the latest change in screening recommendations," Dr. Harper noted.
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