Finally, some answers on how often women should get a Pap test
A Pap test is used as screening for abnormal cells in the cervix to help with early detection of cervical cancer. With the advent of HPV vaccination, we are reminded that vaccine is a primary prevention strategy whereas pap tests are about early detection of disease.We now also have the ability to screen for HPV DNA at the level of the cervix. Today, there remain controversies in cervical screening. Those controversies include — what age should we be starting screening? Should it be 18, 21 or 25 or should it be related to when a female first is sexually active? How often should we repeat screening? Should it be every year, every second year or perhaps a 3 or 5 year interval? Should we be doing paps altogether or should we be using HPV DNA as the primary screen?
In the past, national guidelines have recommended that you begin having Pap tests within 3 years of becoming sexually active or by age 21. You should have a Pap test once per year until you have had two normal test results in a row, and then you only need one every three years. You should continue having tests until you are at least 70 years old. However, in Canada, there is not a national approach to screening and each province has its own approach. For example, Ontario suggests we do Paps within 3 years of being sexually active, whereas Saskatchewan says as soon as being sexually active. Alberta had said within 3 years of being sexually active or age 21. Some provinces suggest the Pap should be done annually whereas others say annually for 3 years and then every 2 to 3 years thereafter. Some provinces suggest we should never stop screening and others suggest age 70 or 75.
Alberta recently started its screening for life (ScreeningForLife.ca) and they now say start Paps at a later age; before 21 is no longer recommended and most women need Paps every three years. The American College of Obstetricians and Gynecologists in 2009 suggested avoid screening under age 21, screen every 2 years from age 21 to 29 and may screen every 3 years from 30 to 65 or 70 if there have been 3 previous normal paps. These suggestions would not apply to women with previous abnormal paps or immune deficiency disease or exposure to DES in utero. Exceptions may also include women with multiple sexual partners.
Experts in Canada are currently reviewing the latest scientific evidence and are in the process of updating these guidelines. Clearly, the lack of consensus has proved confusing. It is also clear that guidelines promoting a recommendation to do less are often looked at with suspicion. It feels as if women are being asked to accept a greater personal risk and perhaps that is about cost containment. But is that really true? Now, the American bodies are coming out with some firm recommendations hoping to add a voice of clarity. What do they say? Two similar sets of guidelines recommend that most women get screened for cervical cancer every 3 to 5 years.
The principal recommendations from the U.S. Preventive Services Task Force (in the Annals of Internal Medicine) and the American Cancer Society and related organizations (in Ca: A Cancer Journal for Clinicians) include:
- Women between ages 21 and 65 without risk factors (such as DES exposure or immunodeficiency) should undergo cytologic screening every 3 years
- Those aged 30 to 65 wishing to extend the screening interval could undergo screening with both cytologic exam and human papillomavirus testing every 5 years.
- Women younger than 21 should not be screened.
- Women older than 65 who have been adequately screened previously should not be screened.
What is the rationale? The majority of cases of cervical cancer are in women who have not been appropriately screened. The data show that in women younger than age 21, screening does not provide a reduction in cervical cancer mortality and incidence compared at screening at age 21. The argument is made that early abnormal tests in young women can lead to harm through interventions such as biopsy leading to outcomes of bleeding, infection and psychological harm.
Remember that we are talking about Pap testing and not screening for sexually transmitted illness. For patients at risk, that is another conversation as to how often that screening should be undertaken.