Doctors must stop misleading women about cervical screening

February 2, 2018 by James Dickinson, The Conversation
While cervical screening has saved countless lives, we overscreen in Canada. Women don’t need to be screened until the age of 25 for cervical cancer. Credit: Shutterstock

Cervical screening is one of the most effective screening tests, responsible for substantial reduction in death from cervical cancer. This disease used to affect two per cent of Canadian women and kill one per cent.

But as with so many good things, the procedure can be overused, and Canadian doctors are overscreening their female patients.

It is time to change cervical screening policy: Start at a later age, and do it less often. Canadian provinces used to start testing from a woman's first sexual activity. In 2011, Alberta changed this to start screening at age 21, and other provinces followed suit.

After examining the evidence, I maintain we should start even later —at age 25. Alberta and British Columbia have made this change; other provinces are considering it.

Screening under age 25 has little impact

Cervical is largely a late result of an earlier infection with human papilloma virus (HPV) —a wart virus. It can develop several years after women become sexually active but mainly shows up when women are in their 40s or older.

I was a member of a team of epidemiologists and a gynecologist who examined the Canadian evidence from before screening started. We found that there was almost no cervical cancer in women under age 25 and very little under age 30. For many years, Canadian doctors performed pap tests when they prescribed contraception, so young were tested annually. Yet this made no measurable difference to the numbers of invasive cancers.

In Britain, a large case-control study found that screening women aged 20 to 24 had little or no impact on rates of invasive cervical cancer up to age 30. Sadly, the few women who do get at these ages have rapidly advancing disease, and neither screening nor treatment seems to help much.

Screening causes harm

If excess screening was only an unpleasant nuisance for women, it might be acceptable, but there is more: It causes harm.

When young women are infected with vaginal warts, it is difficult to distinguish the cellular changes from cancer. Consequently, more than 10 per cent of women under 30 have "abnormal" pap tests, but this rate drops for .

A positive screening test causes anxiety for many women, though HPV warts often go away on their own by the time a repeat test is done.

If the tests appear abnormal, women are referred for further examination by colposcopy (when the cervix is examined under magnification, usually by a gynecologist) and small samples (biopsies) are removed for microscopic examination.

Some biopsies appear abnormal —a "pre-cancer" —and such women may have a larger "cone biopsy" or "loop electrosurgical excision" taken to remove the abnormal area at the entrance of the cervix. This "cures" the pre-cancer, but leaves a weakened cervix. Even though most abnormalities would resolve themselves, a few would not, so doctors treat them all.

The cervix, however, has an important biological role: It holds in babies until the time comes to release them. Women who have had a cone biopsy have a higher rate of pre-term births, and some of these babies die. Having a weakened cervix may not matter for older women who are no longer having babies, but for young women who want to birth children, this is a serious potential harm.

Balancing harms and benefits

What this means is that cervical screening policies and guidelines must balance the potential benefits against the harms of such screening, and recognize that the probabilities change with age.

The Canadian Task Force on Preventive Health Care examined the evidence, and in 2013 recommended that there should be no screening under age 20. Screening should start some time in a woman's mid-20s, with an interval of every three years. Alberta and British Columbia changed their policies in accordance with the science.

Other provinces still start at age 21, and some still screen every two years. The reasons are not clear. Too often Canadians look south to the United States, where early frequent screening persists.

We might do better to check the rest of the world, where few countries start before 25, and some not until age 30.

Women should decide

If women were fully informed, how many would choose to have cervical screening so early and so often? They should have the choice, rather than being given uninformative positive encouragement of the type that's found on many provincial websites.

Physicians need better information to share with their patients, and should not routinely perform tests on at least until their mid-20s.

Women who start sexual activity later in life can wait even longer, since the earliest cancers do not develop until at least four years after first sexual activity, and mostly not until 10 to 20 years later. For those who have been immunized against HPV, the probabilities will be even lower.

Some doctors argue that women should still get regular pelvic examinations and test for sexually transmitted infections (STI). But pelvic examinations look for an enlarged uterus or ovarian disease, which mainly affect older women. And urine tests detect STIs. So doing routine pelvic examinations is unnecessary.

In provinces that do not have registries that remind women to get examined every three years, they may neglect to do so. So some physicians argue women should be told to come at two-year intervals to ensure they come within three years.

This means that compliant women will be screened more often than necessary, and subjected to extra risk of harm, but changes nothing for those who do not attend.

Instead, women and their doctors should follow the science, not inappropriate policies, and women should decide for themselves what is right for them.

Explore further: Facts women and men should know about cervical cancer

Related Stories

Facts women and men should know about cervical cancer

January 22, 2018
January is Cervical Cancer Awareness month and the message from the Centers from Disease Control and Prevention is that "no woman should die from cervical cancer."

Previous screening results important for decision about smear tests after age 60

October 25, 2017
Being screened again after the age of 60 reduces the risk of cervical cancer in women who have previously had abnormal smear tests and in women who did not have smear tests in their 50s, researchers at Karolinska Institutet ...

5 things you should know about cervical cancer

December 1, 2017
(HealthDay)—A little knowledge can go a long way in the fight against cervical cancer.

More than two-thirds of cervical cancer deaths prevented by screening

September 19, 2016
Cervical screening prevents 70 per cent of cervical cancer deaths and if all eligible women regularly attended screening this would rise to 83 per cent, according to research led by Queen Mary University of London (QMUL).

Age matters when it comes to screening for cervical cancer

September 12, 2017
Getting checked for cervical cancer isn't one-size-fits-all. Draft guidelines released Tuesday show age makes a difference.

6 things you need to know about cervical screening

June 13, 2017
It's Cervical Screening Awareness Week, so we're giving a run-down of what you need to know about cervical screening, also known as the smear test.

Recommended for you

Traditional chemotherapy superior to new alternative for oropharyngeal cancers

November 16, 2018
A drug increasingly used in combination with radiotherapy to treat a type of cancer that forms in the tonsils or the base of the tongue is inferior to a previously favored option, according to a large, clinical trial led ...

Repurposing FDA-approved drugs can help fight back breast cancer

November 16, 2018
Screening Food and Drug Administration (FDA)-approved compounds for their ability to stop cancer growth in the lab led to the finding that the drug flunarizine can slow down the growth of triple-negative breast cancer in ...

Standard chemotherapy treatment for HPV-positive throat cancer remains the most effective, study finds

November 15, 2018
A new study funded by Cancer Research UK and led by the University of Birmingham has found that the standard chemotherapy used to treat a specific type of throat cancer remains the most effective.

New 'SLICE' tool can massively expand immune system's cancer-fighting repertoire

November 15, 2018
Immunotherapy can cure some cancers that until fairly recently were considered fatal. In addition to developing drugs that boost the immune system's cancer-fighting abilities, scientists are becoming expert at manipulating ...

Anti-malaria drugs have shown promise in treating cancer, and now researchers know why

November 15, 2018
Anti-malaria drugs known as chloroquines have been repurposed to treat cancer for decades, but until now no one knew exactly what the chloroquines were targeting when they attack a tumor. Now, researchers from the Abramson ...

Researchers identify a mechanism that fuels cancer cells' growth

November 14, 2018
Scientists at the UCLA Jonsson Comprehensive Cancer Center have identified sodium glucose transporter 2, or SGLT2, as a mechanism that lung cancer cells can utilize to obtain glucose, which is key to their survival and promotes ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.