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Pap tests are being both overused and underused, according to the CDC

Cancer cells
CC/Wikimedia Commons/Nephron
Current guidelines recommend that cervical cancer screening begin at age 21 and continue every three years until age 65.

Many women are being screened for cervical cancer when they don’t need it, while many other women who should be screened are failing to receive the test.

Those are the troubling findings from a pair of reports released last week by the Centers for Disease Control and Prevention (CDC).

In both reports, researchers analyzed data from 2000 to 2010 from the Behavioral Risk Factor Surveillance System (BRFSS). The data is pulled from random telephone surveys in which women were asked whether they had undergone a Pap test and, if so, when. The Pap test can detect changes in the cells of the cervix that may indicate early signs of cancer.

According to the most recent government statistics (2008), about 12,000 American women are diagnosed annually with cervical cancer. Tragically, some 4,000 women die from the disease each year. That number would be much higher, however, without the Pap test. Since the test was developed in the 1940s, the death rate in the United States from cervical cancer has plummeted 70 percent, making it one of modern medicine’s greatest success stories. Yet the test is not without potential harms. It produces a large number of false positives, which can lead to unnecessary treatments that sometimes affect future pregnancies.

Current guidelines

The annual Pap test is now a thing of the past. Current guidelines recommend that cervical cancer screening begin at age 21 and continue every three years until age 65. The interval can be extended to every five years for women aged 30 and older who are also being tested for human papillomavirus infection (HPV), a risk factor for cervical cancer. Pap tests are not recommended for women over 65, except for those women whose past test results put them at high risk for developing cervical cancer.

Pap tests are also not recommended for women under age 21, whether or not they are sexually active. As Dr. Otis Brawley, chief medical officer for the American Cancer Society, explained on CNN’s website earlier this year, “many sexually active women under 21 will develop [HPV], which can lead to pre-cancerous lesions. And when doctors see those lesions on a Pap test, they want to treat them. Yet nearly all of those lesions will disappear on their own without residual effects. And those that do not are easily treated years later. Treating them as soon as they're spotted can lead to cervical incompetence and miscarriage down the road.”

Current guidelines also recommend against screening for cervical cancer in most women who have had a hysterectomy. The surgery usually (in 94 percent of cases, according to the CDC) involves the removal of the cervix.

Signs of improvement — and failure

In their analysis of the BRFSS data, CDC researchers found that the percentage of women with hysterectomies being screened for cervical cancer declined significantly in the decade 2000-2010, from 73.3 percent to 58.7 percent.

Yet, that still meant a huge number of women with hysterectomies were undergoing unnecessary testing.

The data also revealed that the number of women aged 18 to 21 who reported never having received a Pap test increased from 26.3 percent to 47.5 percent.

That decline was in step with the guidelines, but, once again, it revealed that a significant number of young women continue to be screened unnecessarily.

While women with hysterectomies and those under the age of 21 are often receiving Pap tests they don’t need, another group of women — those aged 30 to 64 years who do not have health-care coverage and who have not had a hysterectomy — are failing to be screened for cervical cancer. Women in this category were more than a third less likely to have undergone a recent Pap test in 2010 (68.7 percent) than in 2000 (74.4 percent).

Yet it’s women aged 30 to 64 for whom cervical cancer screening is most likely to save lives.

“Underscreening among women with less education, no usual source of health care, and no health-care coverage is well-documented and a persistent cause of health disparities,” notes an editorial that accompanies one of the CDC reports.

A need to further reduce unnecessary screening

As the CDC researchers acknowledge, their findings have several limitations. Most notably, the women in the BRFSS surveys self-reported whether or not they had undergone a Pap test. Self-reports always pose the problem of inaccurate memories, and in this case some of the women may have reported receiving a Pap test when they actually received just a general vaginal exam or other procedure.

Still, the findings from these two reports suggest that many women continue to receive unnecessary Pap tests, despite current guidelines.

“Research is needed to determine how to further reduce unnecessary screening,” the CDC editorial states. “Monitoring Pap test prevalence among U.S. women is important to ensure that resources are targeted to women with the most need.”

Both reports were published in the Jan. 4 Morbidity and Mortality Weekly report (here and here).

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