Screening guidelines shift as the fight against HPV evolves

Nova Scotia is changing its guidelines for cervical cancer screening amid evolving approaches to protecting women and men from the long-term effects of some strains of the human papillomavirus or HPV.

Starting this spring, women are urged to go for their first pap test at age 25 as opposed to 21. In February, the province also started covering the HPV vaccine for people with HIV and men who have sex with other men, in addition to all children in Grade 7.

HPV is the most common sexually transmitted infection and more than 70 per cent of sexually active people contract it during their lives. Most of those people will never know it. Most strains don't have symptoms or long-term effects, but some cause genital warts or precancerous cells in both men and women.

Though the HPV virus causes cervical cancer, Dr. Robert Grimshaw, the medical director of the Nova Scotia Health Authority's Cervical Cancer Prevention Program, said it is "extremely rare" to find it in young women. Even when they contract strains of HPV that cause cancer, their bodies can get rid of it.

"We know that even the precancers, especially in young women, will regress. So they don't all need treatment," he said. 

The standard approach to screening for cervical cancer is regular pap tests, which involve swabbing the cervix, to flag cell abnormalities. Further testing, including testing DNA to see if it specifically contains HPV, is done to determine if those cells could develop into cancer.

Women may be monitored and some of the problem cells may be removed in a process that involves scraping them from the cervix or removing part of the cervix.

But the downside to removing part of a woman's cervix is it could lead to a greater risk of premature labour if she has a child, Grimshaw said.

Multiple treatments could even affect fertility, but he said they also may not decrease the likelihood of cancer developing later in life.

"So if we're not treating those patients, and that treatment only harms and doesn't reduce the risk of cancer, we shouldn't be screening for that," Grimshaw said. 

Women were once urged to get annual pap tests at 18 or as soon as they became sexually active. Since 2013, the Canadian Task on Preventive Health Care has called for routine screening to start at 25. British Columbia and Alberta have already made the change and several other provinces are considering it.

In 2013, Cancer Care Nova Scotia raised its screening age to 21. Now, Nova Scotian women between 25 and 69 are urged to get a pap test every three years.

Health officials across Canada have instituted school-age vaccination and promote cervical cancer screening to curb the effects of HPV, which is also associated with some anogenital, head and neck cancers.

As vaccinated populations age, health officials are now grappling with how best to ensure vaccinated women are covered by screening programs.

Some recent studies have suggested HPV-specific testing involving DNA would work better than pap tests for women who have been vaccinated.

"As more women are immunized, we know the positive predictive value of the pap test will decrease. So we know it's not going to work as well and so we really do need to be thinking about that move," said Kathleen Decker, an epidemiologist in Manitoba who chairs the Pan-Canadian Cervical Cancer Screening Network. 

She said the HPV test using DNA is more sensitive, can be started at an older age and conducted less frequently than a pap test. 

"If we can reduce the number of pap tests a woman needs, or the number of times she needs to be screened, I think that's really good. It's also cost effective," she said.

Countries such as Australia have already moved toward using HPV testing. Decker said changing the approach in Canada would require revising screening guidelines and ensuring people who have a positive HPV test get proper followup.

Data collected in 2018 by the Canadian Partnership Against Cancer, a federally funded independent organization that aims to ensure health policy reflects research, shows no Canadian provinces are using HPV testing to screen for cervical cancer, but Ontario is planning a pilot project.

For now, Nova Scotia is not considering such a move, said Grimshaw. Citing false positives, he said he's not convinced HPV testing would offer a better outcome than pap tests as the first line of defence in cervical cancer screening.

However, the province already relies on HPV testing to followup when a woman has had an abnormal pap and received treatment.

Regardless of the test administered, ensuring women get regular screening is an ongoing challenge. Young people in Nova Scotia are more apt to seek out screening, but women aged 45 to 55 often let pap tests lapse, Grimshaw said.

"Most of the people who develop cervical cancer either haven't ever had pap tests or haven't been tested regularly," he said. "Maybe they've had their children now. When they go to the doctor, instead of going for themselves, they're going for the kids. Pap testing falls off the radar, off the table, sort of."

Guidelines may change again as those who were vaccinated for HPV in school — the eldest of whom are now in their early 20s — reach screening age, since pap tests won't be as effective for those women, Grimshaw said. 

With about 80 per cent of Grade 7 students receiving the required two doses of the HPV vaccine, Nova Scotia has one of the highest rates of compliance with the vaccine in the country. 

Though initially HPV vaccines were only approved for people up until their mid-20s, they've been authorized for women up to 45 and men up to 26 for several years.

Across Canada, health authorities offer varying coverage of the vaccine for people who don't receive it as schoolchildren. In Prince Edward Island for instance, the province offers it for free for adults with risk factors, including that they didn't receive it in school. 

Heather Morrison, P.E.I.'s chief public health officer, said the province wanted to promote immunizations among adults and decided to publicly fund the HPV vaccine for people with risk factors.

Men and women who have sex with multiple partners, have HIV or a history of anal-genital warts, or women with abnormal pap tests are eligible.  

Since the program started in 2016, about 250 people have sought out the HPV vaccine, which typically costs $600 out of pocket.

"I feel like this is certainly the right thing to do with a good vaccine and trying to make sure we have the best coverage and that cost is not a barrier," said Morrison. 

"When I talk to adults, sometimes they're not aware that they need certain vaccines. Sometimes providers need to be reminded… It's part of a broader strategy."

People have to pay out of pocket for the vaccine in Nova Scotia if they miss it in school and their health plan doesn't cover it.

Christine Preston, a registered nurse who works at the Halifax Sexual Health Centre, said a few times a week people in their late 20s and 30s who missed receiving the vaccine in school inquire about whether they should get one.

She said she advises people to consider whether they're at risk of being exposed to new strains of HPV. Typically, people who are in a monogamous long-term relationship are not, she said, but circumstances can change.

"Anyone that is leaving a marriage or entering a dating-world scenario would be way more at risk again for HPV, " she said. 

Grimshaw cautions that research has shown the vaccine is more likely to offer a lifetime of protection when it's given to people who have never been exposed to the virus.

He said it may not be as effective for older people, in part because the vaccine won't treat or get rid of HPV that is ready in people's systems. 

"We know it has some benefit to them, but for sure they're still going to need regular pap testing or regular screening," he said.

MORE TOP STORIES