Co-written with Susan Scanlan.
The pap test (also called a Pap smear) identifies precancerous and cancerous cells in the cervix which, if identified early, can prevent cervical cancer from ever progressing. Early detection prevents cervical cancer.
The pap test has proven to be one of the most effective screening tests in modern medicine. It was integrated into clinical practice in the 1940s and has saved millions of women’s lives since that time.
Only recently has the cause of cervical cancer has been identified as the Human Papillomavirus or HPV. Understanding the cause of cervical cancer has led scientists to understand how the disease progresses from infection to cancer. These discoveries have led to new recommendations about when pap testing should be started and how often it should be done.
Current Recommendations for Cervical Cancer Screening
The U.S. Preventive Services Task Force (USPSTF) recommends that women who have a cervix have a Pap test every three years between ages 21 – 65.
Every five years, starting at age 30 and until age 65, women are advised to get a Pap test plus HPV DNA testing to screen cells for certain high-risk types of HPV.
The USPSTF does not recommend cervical cancer screening for women under 21 (i.e., neither Pap nor HPV DNA tests), because the tests are unlikely to find any problems. Similarly, the USPSTF does not recommend HPV DNA tests for women under 30, because almost everyone will test positive for the virus at least once. Even though the virus almost always goes away on its own, a positive HPV test increases people’s health care costs and anxieties. Some clinicians may order a HPV test as follow-up to an abnormal Pap test, but HPV DNA test is not meant for general screening or simply to determine HPV status.
These recommendations, released in March 2012, are significantly different than earlier recommendations. While it is still important to get regular check ups with a health provider, it is no longer necessary to start pap tests as early or in most cases to have them every year.
Why Are There New Guidelines?
Guidelines from the U.S. Preventive Services Task Force (USPSTF), released in 2012, and from the American College of Obstetricians and Gynecologists (ACOG), released late 2009, say women should wait longer to begin cervical-cancer screening and that they should be screened less frequently. Some women are confused about the recently changed recommendations. On the heels of similar changes to breast cancer screening guidelines, its understandable that many women might see this as a step backward.
On the contrary, the new cervical cancer screening recommendations reflect advances in our understanding of this disease and in tools now available to prevent it. More importantly, they present an opportunity to educate women about the significant opportunity we have to further prevent if not eliminate cervical cancer.
To understand the rationale for these changes, its important to first know how the disease develops.
Cervical cancer is caused by high-risk types of the human papillomavirus (HPV), a common sexually transmitted infection. Most women will have HPV at some point in their lives, but their immune systems will typically clear the virus without symptoms or treatment. HPV infections that persist over time — typically many years — can cause cell changes that can potentially lead to cervical cancer. Because cervical cancer is slow-growing, it generally allows ample time for screening to detect problems that can be treated before the cancer can develop. The majority of women who die of cervical cancer in the U.S. have either never been screened or have not been screened in many years.
A Pap test is the traditional means of screening for cervical cancer. It involves examining cervical cells under a microscope to detect abnormalities that can then be treated, if necessary. (For more information, see Cervical Dysplasia & Cervical Cancer.) Since its use became widespread 60 years ago, the Pap test has helped to significantly reduce cervical cancer rates. So, if the Pap test has been such a success, why change the guidelines?
First, newer research shows that cervical cancer is extremely rare in women under 21. Cervical abnormalities among sexually active girls in this age group are common, but they typically go away on their own. Newer studies, however, show that treatment for these abnormalities that would most likely resolve themselves can cause later pregnancy complications, such as premature birth. This is one instance in which treatment can cause more harm than good. By delaying the start of screening, we can hopefully avoid unnecessary treatment.
The rationale for less frequent screening is similar. Evidence shows that screening with a Pap test every year does not offer any additional benefit over screening every two or three years. Waiting longer between screenings can help avoid unnecessary treatment of abnormalities that likely will go away on their own.
Also, new technological advances offer women 30 and older — the group most at risk for cervical cancer — more protection against this disease. For these women, an HPV test is now available and uses molecular technology to determine whether HPV is present.
An HPV infection that continues for years is what leads to increased risk of developing cervical cancer. If an HPV infection is found, a woman can be monitored more closely by her clinician. A negative HPV test in tandem with a normal Pap test can give a clinician and her patient increased reassurance that the woman is not at risk of developing cervical cancer for at least the next three years. The HPV test also is used for women of all ages to help clarify inconclusive Pap test results. The HPV test is not used routinely in women under 30 because HPV is so common in this age group that a positive HPV test could lead to unnecessary treatment.
While screening is critical to preventing cervical cancer, two HPV vaccines — the first-ever vaccines to fight a cancer — are now FDA-approved and offer significant potential to help reduce cervical cancer rates.
Remember, these new screening recommendations are simply guidelines and that clinicians, in conjunction with patients, need to determine the most appropriate cervical cancer prevention approach for each woman. These new guidelines provide an opportunity for more conversation on this issue between women and their health-care providers.