In the past 60 years, the number of deaths that occur from cervical cancer has declined by over 70% in the United States. This dramatic decrease is attributed to the widespread use of Papanicolaou (Pap) tests —screening tests for cervical cancer. Today, over 80% of women have had a Pap test within the past three years.

Regular Pap tests will help detect precancerous growths or identify cervical cancer in its early stages, when it is highly treatable. But how often should women get Pap tests? The consensus is leaning toward once every three years. The U.S. Preventive Services Task Force and the American Cancer Society both suggest up to three-year intervals between screenings. Despite these recommendations, many physicians perform Pap tests annually.

A study in the October 16, 2003 issue of the New England Journal of Medicine found that extending the interval between Pap tests from one to three years would increase a woman’s risk for cervical cancer by approximately 3 in 100,000. Furthermore, the researchers calculated that it would take more than 42,000 Pap tests and 2,300 colposcopic exams (close examinations of the cervix) to prevent one additional case of cervical cancer through annual screenings.

About the Study

The researchers used data from the Centers for Disease Control and Prevention’s (CDC) National Breast and Cervical Cancer Early Detection Program. From January 1991 to March 2000, 938,576 women under the age of 65 participated in this program, which provided cervical-cancer screenings to low-income, underinsured women.

The women were screened with Pap tests. Diagnostic testing to detect precancerous growths or cancer, most often by using an instrument called a colposcope, was performed following abnormal screening results.

In women who had three normal Pap tests in a row, the researchers determined the excess number of cervical cancers that would have occurred had these women extended the interval between Pap tests from one to three years. Since very few women would develop cancer, the researchers had to estimate the rate at which precancerous growths would have progressed to cancer.

The researchers also calculated the number of additional Pap tests and diagnostic procedures it would take to avert one additional case of cancer annually for every 100,000 women screened.

The women were divided into groups according to their age.

The Findings

Among the 32,230 women who had three consecutive negative Pap tests, the researchers estimated that extending the interval between screenings from one to three years would have the following effects:

Age groupAdditional cases of cancer per 100,000 women
Under 305

They also determined that avoiding just one additional case of cancer by annual screening would require the following:

Age groupAdditional Pap testsAdditional colposcopic exams
Under 3042,6212,364

These calculations could not be made for women ages 60-64, since extending the interval between screenings had no effect on risk of cervical cancer in this group.

How Does This Affect You?

Do the advantages of annual screening outweigh the disadvantages? Will women remember to go for screenings every three years rather than every year?

Since the excess risk associated with three-year intervals between Pap tests was so small, these results suggest that annual screenings may not be necessary in women who have had three normal Pap tests in a row. The excess risk found in this study is comparable to the risk of a man between the ages of 45 and 64 developing breast cancer. Excessive screening is costly, increasing the price of health care. Also, the anxiety and hassle associated with getting a Pap test every year is no small matter.

However, it is possible that extending the interval between Pap tests will cause more women to skip screenings. Extending the interval between screenings may increase the risk that women forget to schedule a screening or delay having a Pap test for more than three years.

So how often should you get Pap tests? You and your doctor should make that decision. If you are at low risk for cervical cancer and have had three negative Pap tests, you may be able to extend the interval between Pap tests to three years. If, however, you are at increased risk for cervical cancer or do not already come in for regular screenings, your doctor may advise you to have a Pap test annually.

Factors that increase your risk for cervical cancer include:

  • Having sexual intercourse before age 18
  • Having multiple sexual partners
  • Having a partner that began sexual intercourse at a young age, had many sexual partners, or was previously married to a woman who had cervical cancer
  • Having been diagnosed with sexually transmitted human papillomavirus (HPV)
  • Having a partner who has been diagnosed with HPV
  • Smoking
  • AIDS and other causes of a weakened immune system

Keep in mind that Pap tests are only part of a well-woman visit with your gynecologist, which also consist of breast and other cancer screenings, as well as discussions on a wide variety of issues, including menstruation, birth control, preconception care, sexually transmitted diseases, and sexual activity. Many women use their gynecologist as their primary health care provider, so for these women regular visits may also be an opportunity to get immunizations and other screenings.