Why the HPV test is replacing the Pap smear to detect cervical cancer in Canada – National | Globalnews.ca
Changes to cervical cancer screening for women are underway in Canada that could help detect high-risk pre-cancerous infections.
At least two provinces have already said they would replace the old Pap test and move to the human papillomavirus (HPV) test as the primary screening method for cervical cancer. Several others are also looking at making the switch.
Prince Edward Island announced in May that the HPV test would be used instead of the Pap smear at three-year to five-year intervals, as it can detect high-risk strains of the virus, which are more likely to cause cancer.
Quebec announced last year that it would offer HPV testing as the primary screening test for cervical cancer every five years to all women aged 25 and older in the province in May 2022, saying it is “more sensitive than the Pap test” — which is recommended every three years.
HPV is one of the most common sexually transmitted infections in Canada, with more than 70 per cent of sexually active adults estimated to develop it at some point in their lives.
The World Health Organization says HPV is the primary cause of cervical cancer especially if the infection persists, but most infections resolve on their own without symptoms.
The move towards HPV testing as the first stage in a cervical cancer screening program would not only help better detect precancer or cancer but could cut overall costs as it is done less frequently, experts say.
Dr. Togas Tulandi, professor and chair of obstetrics and gynecology at McGill University in Montreal, said the switch to HPV testing is a “very good idea.”
“In the next several years, maybe decades, we might be able to eliminate cancer of the cervix by doing this test,” Tulandi said in an interview with Global News.
As more Canadian healthcare providers mull the transition, other countries such as Australia, the Netherlands and the United Kingdom, have already adopted the HPV test for cervical cancer screening.
Cervical cancer rates have dropped in Canada thanks to screening and vaccination efforts.
The Canadian Partnership Against Cancer has set a target in its action plan to eliminate cervical cancer in the country by 2040.
The HPV test is not that much different than the Pap test in that the sample is collected in the same way for both.
As in the Pap test, a speculum is inserted in the vagina to separate its wall and a small brush is used to collect cells from the cervix, which leads into the uterus, according to the Canadian Cancer Society.
The main difference is the lab testing.
The HPV test uses polymerase chain reaction (PCR) that checks the DNA or mRNA of high-risk types of HPV.
However, the Pap test will look for precancerous cervical cells.
“The difference is Pap test is to detect the presence of abnormal cells,” Tulandi said.
“With HPV test, it is to check the virus itself, so before the changes occur in the cervix, it could be detected.”
Unlike the Pap test, where a cytopathologist is needed, a machine will do the HPV testing, Tulandi said.
“Also it (the HPV test) could be done by the patient themselves if they are far from medical health facilities. And interestingly, the result is almost as good as the test done by a doctor or nurse.”
An article published in Canadian Medical Association Journal last year noted that the Pap test may miss “almost half of existing abnormalities” but repeat testing every two to three years can mitigate harms from previously missed detections.
The HPV test has a higher sensitivity than the Pap test — 94.6 per cent vs 55.4 per cent, but a lower specificity — 94.1 per cent vs 96.8 per cent, the CMAJ article said.
“This means that a greater proportion of patients without cervical disease are likely to receive a positive test result,” the authors from Toronto’s Mount Sinai Hospital wrote.
“However, with increasing HPV vaccine uptake and decreasing prevalence of high-risk HPV infection, HPV testing is expected to confer fewer false positives than Pap testing, while maintaining a strong negative predictive value.”
The report’s authors added that HPV testing “will soon replace the Pap test for primary cervical cancer screening in Canada, as it is a more sensitive test that has been shown to be cost-effective and safe.”
Where do provinces stand?
When asked about Health Canada’s stance on HPV testing replacing the Pap test in the country, the Public Health Agency of Canada told Global News it “recognizes the importance of screening to prevent cervical cancer, and is aware that a number of provinces in Canada are considering a shift to the use of HPV screening.”
It noted, however, that the provinces and territories are primarily responsible for the administration of health services, including testing and medical advice.
Global News reached out to all of the provinces and territories about whether they plan to follow Quebec and P.E.I. in replacing the Pap test with HPV screening.
Nova Scotia Health’s cancer care program said it is planning a transition to primary HPV screening, but the planned rollout could take at least three years to implement.
“Regular Pap tests are still the most effective way to prevent cervical cancer and find it early when treatment is most effective,” the province told Global News in an emailed statement.
But it added: “Primary HPV testing is a better way to screen people who have already received the HPV vaccination.”
In New Brunswick, activities to support the transition to HPV primary screening are scheduled to start in the fall.
“The New Brunswick Cancer Network has completed initial research and analysis to identify steps needed to transition from the current pap test-based screening to HPV primary screening with an option for the self-collection of samples,” the province said in a response to Global News.
Plans to move toward primary HPV testing are also underway in Saskatchewan.
“The Saskatchewan Cancer Agency is currently updating cervical screening guidelines to include HPV reflex testing, with implementation later this summer, the province said.
Manitoba introduced HPV reflex testing in February 2022, to screen for high-risk HPV (hrHPV) on abnormal Pap tests to determine which patients require a follow-up diagnostic procedure versus those who can return to routine screening.
“The enhanced process reduces unnecessary follow-up testing and treatment with improved cervical cancer outcomes for Manitobans by ensuring those most at risk receive appropriate interventions,” a Shared Health spokesperson said.
Ontario Health said it is working to implement HPV testing, “which is reflective of the latest research and advances in technology.”
“Ontario Health (Cancer Care Ontario) is currently undertaking a competitive bid process to select the test system as well as the laboratory partner(s) to perform the HPV testing,” a spokesperson told Global News in an email.
Nunavut and Northwest Territories are in the process of reviewing their respective cervical cancer screening programs.
Nunavut’s Department of Health said discussions are ongoing regarding the use of HPV tests to detect cervical cancer.
While no decision has been made by NWT, the territory’s health authority said it will develop recommendations for best practices and potential revisions of the current guidelines for cervical cancer screening which may include HPV testing.
Global News did not hear back from Newfoundland and Labrador, Alberta, B.C., and the Yukon by deadline.
There are more than 100 types of HPV viruses, according to the Canadian Cancer Society, but not all of them are high risk or can lead to cancer.
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