“It’s coupling the almost thousand women that we would have to treat for these cervical abnormalities that might go away versus the one or two cases of cancer a year,” Dr. Van Niekerk said. “It isn’t the best balance of benefit and harm.”
The B.C. Cancer Agency says research shows screening every three years is as effective as doing it every two. It notes that cervical cancer goes through a pre-cancerous phase that lasts for years before evolving, which makes the disease very preventable if detected early on.
Meanwhile, Dr. Ogilvie is leading the province’s HPV FOCAL study – a 25,000-person trial that compares standard Pap screenings with HPV testing, in an effort to determine which option should be used as a primary testing method.
The human papillomavirus is a very common sexually transmitted disease – about three-quarters of sexually active people will get it at some point – but some strains of HPV are known to cause cervical cancer.
Pap tests and HPV tests are similar, though they differ in how samples are processed. With a Pap, cells scraped from the cervix are examined under a microscope for abnormalities, while an HPV test looks for the virus’s DNA within the cells.
“We want to wait for the clinical trial to really define the optimal way to roll this out first,” Dr. Ogilvie said. “That is why I think the province is being quite methodical in having a step-wise approach, starting first with the new cervical cancer screening guidelines with Paps.”
The results of the trial, the largest of its kind in Canada, are expected to be available within the next year.
Dr. Ogilvie said she thinks the province is keen to consider HPV testing – a method she says is more accurate than Pap testing – as a way to further optimize cervical screening.
“We will definitely be looking at the data and making a decision in the near future, on whether HPV DNA testing might be more appropriate in certain age groups,” Dr. Van Niekerk said.
“Because we know most cancers are caused by infection by HPV, it really puts us earlier in that pathway to cancer,” he said, adding that women who test negative for HPV are less likely to develop abnormalities over a longer period of time, so it might even be possible to screen less frequently for those women.
“The increased detection and the longer protection are the two things we are really very interested in,” Dr. Van Niekerk said.
Dr. Ogilivie said this new method might come with an added benefit: the ability to bring testing to people who aren’t already getting it, since HPV testing can also be done by a self-collection method.
“What would likely happen is that as part of rolling out HPV testing, [the province] would consider a self-collection arm, to really try to improve uptake in those women who haven’t been able to come in for a pelvic exam, for whatever reason.” she said.
“We are very interested in that option to allow women who are currently not participating in screening to screen,” Dr. Van Niekerk said. “It appears from the data that a self-collected HPV sample is almost as accurate as a physician-collected HPV DNA sample.”