Cervical cells collected in Pap tests: normal cells on the left, precancerous cells on the right. Ed Uthman/Wikimedia Commons

My regular readers know that I frequently bemoan the fact that we have no effective way to test for most cancers, and that in many cancers early diagnosis does not improve survival. Cervical cancer is one of the few exceptions. Since Georgios Papanikolau developed the test named after him, the Pap test has dramatically reduced the incidence and mortality of cervical cancer.

More recent advances have shown that cervical cancer is caused by human papilloma virus (HPV), a sexually transmitted infection. Specific testing for HPV is now frequently performed in addition to the Pap test, and a vaccine against the most dangerous strains of HPV is likely to further decrease cervical cancer incidence.

We also now understand that the changes that HPV cause are detectable years before cervical cancer occurs, so the interval between tests can be quite long. Current recommendations are for all women between the ages of 21 and 65 to have a Pap test every three years. If HPV testing is also used, women over 30 can be safely tested every 5 years.

Women over 65 who have been previously tested and have had normal test results are unlikely to benefit from further testing. Also women who have had a total hysterectomy (surgery in which both the uterus and cervix are removed) do not need further Pap tests, because they don’t have a cervix. (An important exception is women who have had a hysterectomy because of cervical cancer or pre-cancerous changes.)

This week brings us evidence of too much of a good thing. The current issue of Morbidity and Mortality Weekly Report (MMWR) published a survey of women over 65 and women who have had hysterectomies. It asked them if they had a recent Pap test. Two thirds of women over 65 answered affirmatively as did 59% of women who have had hysterectomies. I found that as surprising as if 59% of bald men were still going to their barber regularly. It’s hard to know what’s behind this behavior. These women can’t benefit from the tests they’re undergoing. Perhaps this is a manifestation of long-established habits for both the doctors and the patients. Another possible explanation is that some of the women surveyed are simply wrong. The study didn’t actually check medical records, and some of the women may have thought that they had been tested when they hadn’t. Obviously, the most pernicious possibility is that many doctors are still recommending useless testing to patients who trust them. (If Medicare paid for haircuts one wonders how many bald men would still go to their barbers, just for the attention and social interaction, and how many barbers would sent reminder postcards to their bald patients.)

So if you’re between 30 and 65 and are having both Pap tests and HPV testing and your results have been normal, give yourself 5 years between tests. And if you’re over 65 and your tests have been normal, or you no longer have a cervix, congratulate yourself for permanently escaping cervical cancer and feel free to forego further testing.

Learn more:

Pap Tests For Cervical Cancer Are Often Wasted (Shots, NPR health news)
CDC: Women with hysterectomies getting unneeded Paps (USA Today)
Cervical Cancer Screening Among Women by Hysterectomy Status and Among Women Aged ≥65 Years — United States, 2000–2010 (MMWR)
Announcement: Cervical Cancer Awareness Month — January 2013 (MMWR)
US Preventive Services Task Force recommendations for cervical cancer screening
My post in 2009 summarizing the recommendations for Pap tests: Should You Have a Pap Smear?