HPV tests or Pap smear? An expert weighs in on cervical cancer screening

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As Prince Edward Island replaces Pap tests with HPV (human papilloma virus) testing to screen for cervical cancer, an expert says that route is more effective in determining the level of risk.

According to Ontario gynecologist Kim Alexander, about 95 per cent of cervical cancers are caused by HPV.

"Cervical cancer is a sexually transmitted disease… so if we know your HPV status, we actually know your level of risk," said Alexander.

With HPV testing, she added, "we can actually know whether you have the virus that causes cancer. That's super powerful," she added.

What is HPV?

Health Canada outlines HPV is one of the most common sexually transmitted infections (STIs) in the country — and worldwide.

There are more than 100 types of HPV, most of which cause no symptoms and go away on their own.

Some types, however, can infect areas such as the hands and feet, according to the federal agency.

"Other types target the anogenital area and are transmitted during vaginal, or oral sex or during intimate skin-to-skin contact with someone who is infected."

HPV causes almost all cervical cancers but is also linked to cancer of the throat, oral cavity, penis, anus, vagina or vulva.

"It is possible to be infected by more than one type of HPV at a time," Health Canada stated.

It estimated as many as 75 per cent of sexually active men and women will have at least one type of HPV infection in their lifetime.

How to test for HPV?

According to Dr. Alexander, HPV testing is done in a similar way to a Pap test, where a swab gets used to collect a small sample of cells from a cervix or vagina that may have the cancer-causing virus present.

In Canada, HPV testing may not be covered by a provincial and territorial health program and people may have to pay for it out-of-pocket.

"Where I am in Ontario… if my patient gets a funny Pap test, I can actually call into the lab and ask them to run an HPV [test] on it," said Alexander.

"Or I can check a box when I submit that Pap specimen that says please run HPV at this time… and because we really want to get a good idea about their ongoing risk, most of my patients do agree to pay the $100 that it cost to process their HPV test," she added.

Unlike the Pap test, which requires a cytopathologist to detect precancerous cervical cells, testing of a cervical sample for HPV subtypes uses polymerase chain reaction (PCR), the Canadian Medical Association Journal explained.

"One of the bonuses of implementing [HPV testing] now is that the machines we're using are the same machines that they used for COVID," Alexander explained.

"That's actually going to help speed up implementation."

Are HPV tests better than Pap tests?

Alexander said HPV testing comes positive on average 15 years before a cancer develops. A Pap test may never become positive — even if a person has the virus.

"The false rate of Pap test is in the range of 10 to 20 per cent, so we can miss things on the Pap test," she claimed.

"HPV testing missing rate is close to zero… it’s very effective in determining your risk," said Alexander.

The Canadian Medical Association Journal stated: "Pap testing has a high specificity of 96.8 per cent but a low sensitivity (55.4 per cent), which means that screening misses almost half of existing abnormalities."

Essentially, HPV testing is more accurate than a Pap test, and can now be done faster than before.

How often should you get an HPV test?

Because HPV testing is able to catch problems so early, Alexander said it only needs to be done every five years, in comparison with the three years recommendation of Pap tests.

"The awesome thing about HPV testing is that it gives you a risk before you might even be developing a problem… And ideally, we're gonna see that HPV test changed to negative for most people who get the virus," she explained.

Alexander added 80 per cent of people will clear the virus from their body within two years, especially patients in their 20s.

"Most people are not going to get cancer, for most people the virus is going to be a minor blip in their life…but at some point as we get older, that gets more challenging," Alexander said.

Why is HPV vaccination important?

Alexander said cervical cancer "is a vaccine preventable disease."

The vaccine is generally available for kids in school and for people up to the age of 26, but people who are older can get it too.

The HPV vaccine commonly used is the HPV9 vaccine, also known as Gardasil 9. This vaccine protects against nine different types of HPV and protects against seven types that can cause cancers of the cervix, anus, mouth and throat, penis, vagina and vulva, and two types that can cause genital warts.

"You also provide vaccines to at-risk populations," said Alexander.

At-risk people include those who:

• have had genital warts

• have had abnormal Pap tests

• have frequent new sexual partners

The vaccine is also recommended for people who are in midlife too, aged 40 and up.

"Doctors and non-doctors have stereotypes about who's at risk, and that married people are not at risk for acquiring the HPV virus," Alexander claimed.

"But midlife relationship instability is so common, like divorce, affairs and those who decide to have non-monogamous relationships, which can put people in midlife at risk."

Unlike younger people who have a higher chance of clearing the virus, only 60 per cent of people in their 40s clear it within two years.

"This is why midlife vaccination is something to consider… because the virus is just there for longer, with more ability to cause problems for people," said Alexander.

What's next for HPV testing in Canada?

Alexander said she hopes other provinces across Canada follow in PEI's footsteps in making HPV testing the primary screening for detecting abnormalities.

"There's a lot of discussion about a future possibility of self-swabbing," she added. "It's definitely something that care providers and policymakers are considering."

She said the goal of health authorities in Canada is to get HPV testing out as quickly as possible, and self-swabbing can help with that.

"Certainly for unscreened populations, that will probably be where we start for self-swabbing, so the folks who are reluctant to come and seek care providers, especially our LGBTQ+ folks and our remote community folks."

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