FAQ: the pap smear

The Pap smear is a medical success story, largely credited with cutting the rate of cervical cancer by 70 to 90 percent in many countries over the past half century. Although the Pap smear has near-sacred status in women's health care, new approaches to screening for cervical cancer are on the horizon. The following guidelines will tell you more.

Named for its inventor, George N. Papanicolaou, MD, the Pap smear (also called the Pap test) detects cancer cells and abnormal cells that may become malignant.  All women, though some may not require annual exams, and older women may not need Pap tests anymore.

The major cause of cervical cancer is human papillomavirus (HPV), which is typically transmitted through sexual intercourse. Most guidelines recommend that women begin having annual Pap smears within three years of their first sexual activity or by age 21. Some physicians believe that women over 30 who have had three consecutive negative Pap smears need to be screened only every two or three years. Some doctors worry, however, that women who don't have annual Pap smears may end up skipping other important screening exams that gynecologists perform.

Regardless of your schedule for Pap smears, you should still plan on having other routine screening tests, including pelvic exams, clinical breast exams and blood tests for sexually transmitted diseases. Women aged 65 to 70 may stop having Pap smears if they have had three consecutive negative tests in a 10-year period. A woman who has had her cervix removed doesn't need to have a Pap smear unless the surgery was performed because she had cervical or uterine cancer. (Keep in mind that the cervix is not always removed as part of a hysterectomy; in such cases, regular Pap smears are still recommended.)

The Pap smear is only modestly sensitive, which is why routine testing is necessary to guard against cervical cancer. A Pap smear will detect cervical cancer or abnormal cells that could become cancerous about 50 to 75 percent of the time. The test is even less likely to spot cells that are only mildly abnormal.

To perform a Pap smear:

• doctor, nurse or other trained health care professional removes cells from the cervix with a special scraper (sometimes called a spatula) and/or brush.
• The cells are smeared on a glass slide and analyzed in a lab. Problems with preparing or reading the slide may affect the test's accuracy.

However, cervical cancer develops over many years, so regularly scheduled Pap smears usually detect the disease while it's still treatable. As with many screening tests, the Pap smear produces a significant number of false-positive results. The risk that a Pap smear will cause a false alarm rises as a woman ages. In one four-year study, 2,500 post-menopausal women had annual Pap smears, which produced 110 abnormal results and led to 231 additional tests, including biopsies. Yet none of the women had cervical cancer, and just one required additional treatment for precancerous cell growth. On the other hand, if your Pap smear is negative, you can breathe easy; the chances are 95 percent or better that you do not have cervical cancer.