Women still need pap test, just not as often

Q I've had a Pap test every year for 20 years, since I was about 25. It's always normal. Do I still need one every year?

A: The answer used to be yes. The reason was that doing the test often would help catch cancer of the cervix at its earliest and most curable stage.

However, studies showed that less frequent Pap tests for younger women caught just as many early cancers. The studies also showed that many older women with repeatedly normal Pap smears (like you) had an extremely low risk of ever getting cancer of the cervix.

These studies led to new guidelines issued in 2012. They suggest that women ages 21 to 65 have a Pap test every three years or, for women ages 30 to 65 who want to lengthen the screening interval, have a combination Pap test and human papillomavirus (HPV) test only once every five years. (Most cervical cancers are caused by specific types of HPV, a sexually transmitted virus.)

In addition, most women ages 65 and older, and women who have had a hysterectomy (and no longer have a cervix), do not need to have Pap tests. The exceptions are women with a history of precancerous cells, cervical cancer or abnormal Pap/HPV tests.

The new recommendations stem from a better understanding of how cervical cancer develops. It doesn't develop very rapidly. Rather, there are clear precancerous stages that take years to progress.

What's the downside of an annual Pap test?

For young women in particular, frequent Pap tests can lead to false positive results (the test result suggests a possible cancer, but there really is no cancer).

That false positive result can lead to unnecessary worry and anxiety. It also can lead to further, and invasive, diagnostic tests such as a colposcopy and biopsy of the cervix. These invasive diagnostic tests, in turn, can cause vaginal bleeding, infections and pain.

Less often, the Pap test and HPV test can produce false negative results (the test result is normal, but there really is a cancer). With that false reassurance, a woman may be less likely to bring worrisome symptoms (like bleeding between menstrual periods or pain) to her doctor's attention.

Unfortunately, the tests we have available to screen for cancer are not perfect. Since the tests are imperfect, and could cause complications, you'd want to have them when they are more likely to benefit you than to harm you.

That's why recommendations as to how often a woman should have a Pap test are based on the risks of a false positive or false negative result, and how likely cervical cancer is in the person having the test.

For example, cervical cancer is less common in young women than in women in their late 50s.

The bottom line: You still need the Pap (and the HPV) test, but not as often as you did in the past.

• Dr. Komaroff is a physician and professor at Harvard Medical School. For questions, go to AskDoctorK.com.