Study Boosts Cervical-Cancer Rate Estimates

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Study Boosts Cervical-Cancer Rate Estimates

News Review from Harvard Medical School

May 13, 2014

News Review From Harvard Medical School -- Study Boosts Cervical-Cancer Rate Estimates

A new study questions the way U.S. cervical-cancer rates are calculated and finds much higher estimates. Rates rose the most among women in their 60s and black women. Previous studies have included all women, even those who have had the uterus and cervix removed by hysterectomy. But the new study notes that a woman without a cervix would not be able to develop cervical cancer. Researchers used numbers on cervical cancer rates taken from a government registry in 18 states. They estimated hysterectomy numbers based on a national health survey. They calculated that about 11.7 cervical-cancer cases per 100,000 women are diagnosed each year. Rates were highest between ages 40 and 44 and then fell. But cervical cancer rates were 18.6 per 100,000 when only women who still had a cervix were included. And rates kept rising with age. The highest rates were between ages 65 and 69. But current guidelines say most women age 65 and older are at low risk and no longer need tests to screen for cervical cancer. The journal Cancer published the study. HealthDay News wrote about it May 12.


By Lori Wiviott Tishler, M.D.
Harvard Medical School


What Is the Doctor's Reaction?

Articles that question current medical wisdom are always thought-provoking.  This is one!  This article, published yesterday in the journal Cancer, suggests that we may be underestimating new cases of cervical cancer. Estimates may be particularly low for older women and black women.

The cervix is the very bottom part of the uterus.  Human papilloma virus (HPV) causes most cervical cancers.  Pap smears and HPV testing can help doctors to detect early cancers, which can be cured. 

Current guidelines teach that women over the age of 65 have a very low risk of developing cervical cancer. For most low-risk women over age 65, current wisdom says that doctors can stop doing Pap tests and feel confident they will not miss cases of cervical cancer.

This article turns that upside down. It does so by looking at a very simple, but incredibly important math problem.

The new idea is that we have been doing the math the wrong way when figuring cervical cancer rates. Previous studies have included women who have had hysterectomies. But the authors correctly state that these women don't get cervical cancer. That's because they don't have a uterus or a cervix.  When we remove those women from the equation, the percentage of women with cervical cancer becomes a lot higher.

A quick example: Pretend that 1 in 100 women get cervical cancer.  That's 1%.  Now imagine that 50 of those women had hysterectomies. If we remove them from our calculation (because they can't get cervical cancer), then the rate becomes 1 in 50, or 2%. 

Simply put, the authors of this study did the above math problem with much more appropriate numbers.  They looked at new cases of cervical cancer among women who haven't had hysterectomies.  Here's what they found:

  • Rates of cervical cancer continue to increase in women after age 35.  In the uncorrected group, including women with hysterectomies, these rates decline after age 35.
  • The highest rate of new cases was in women ages 65 to 69.  Previous data suggested that the highest rates were in women ages 40 to 44.
  • Older, black women were most affected by the change in calculation.

These findings are striking.  At least one previous study suggests that they are also accurate.  If other studies confirm these findings, then our current recommendation to stop cervical cancer screening at the age of 65 may be not be appropriate. 

I will be closely watching the data and future statements from the U.S. Preventive Services Task Force and the American College of Obstetricians and Gynecologists. I want to see how this important re-calibration of the data affects their advice. I will be thinking carefully about individual patients and their risk. I'll talk with them about whether we should screen for cervical cancer beyond age 65.


What Changes Can I Make Now?

All women who have ever been sexually active should be screened for cervical cancer starting at age 21. This includes women who have had sex only with women. If Pap tests are normal, then screening can take place every 3 years. Women over 30 with normal Paps and a negative HPV test can be screened every 5 years.

If you have had a hysterectomy because of cervical or uterine cancer, you may need screening more often. If you have had a hysterectomy because of other conditions, such as fibroids or heavy periods, then you may not need Pap tests at all. 

Women who have a history of abnormal Paps or have tested positive for HPV need more frequent screening. This could be as often as once a year. 

Current guidelines suggest that women with normal Paps and negative HPV tests can stop having routine Pap tests at 65.  Today's article suggests that this advice may change.  If you are in your 60s, talk to your doctor about your personal risk and the potential for a change in advice.


What Can I Expect Looking to the Future?

I think we can expect to see more studies looking at this question.  If other studies bear out the increased risk of cervical cancer in older women who have not had hysterectomies, then I think we can expect changes in current screening advice.

Last updated May 13, 2014

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