Iqaluit researcher advocates for better pap test
Cervical cancer a leading killer of Nunavut women
A public health researcher in Iqaluit wants Nunavut women to know that new screening methods are available that could lead to earlier detection of cervical cancer and the sexually-transmitted virus believed to cause it.
In a presentation to the International Congress on Circumpolar Health in Nuuk, Greenland, this month, Sylvia Healy, an epidemiologist with the Government of Nunavut, presented the findings of a study of more than 1,000 pap tests taken from women in the Baffin and Kivalliq regions.
Cervical cancer is one of the leading killers of Nunavut women. It represented 35 per cent of all cancers diagnosed in women in the Northwest Territories between 1991 and 1996.
And studies have shown that the human papillomavirus (HPV) is present in more than 99.7 per cent of cervical tumours.
Healy, who performed the study as part of a master’s degree in epidemiology, wanted to investigate the relationship between cervical cancer and HPV, and determine the prevalence of cancerous HPV in Nunavut.
She showed that testing for DNA strains of HPV can predict the onset of cervical cancer in older women. And she found that simply by using a different type of test for cervical cancer itself, physicians and laboratory technicians could provide Nunavut women with earlier and more reliable diagnoses.
“With the old test, you had a scraper and you had a brush, and you put the scraping first and the brush second and spray it. There are just too many steps, and therefore, errors,” she said in an interview.
As a result, the pap test has an accuracy rate of about 51 per cent.
“That means half the people they say are negative may not be,” she said. “Even though this is a test that has enabled us to successfully drop the rate of cervical cancer historically, it still has a lot of limitation.
Healy’s study used a test called liquid-based cytology. “With this new test, it just scoops up all the cells and puts them into a liquid. And the liquid goes to the lab and the lab makes all of the concentrations of the samples equal.”
The accuracy rate of liquid cytology is between 74 and 90 per cent.
“Very accurate. So we have a better test,” she said. “I did the study three years ago and I decided to present it at the international conference because I really want to advocate for the change.”
But test results alone may not be enough to persuade number-crunchers within the GN. The deciding factor will be cost. HPV testing is significantly more expensive than pap tests and liquid cytology because it involves costly DNA analysis.
However, the current practice is expensive too. Because it is unreliable, physicians have become overly conservative in the way they manage treatment, repeating the test several times and referring patients to a southern gynecologist even if results are slightly abnormal.
“So it becomes a very expensive and cumbersome method of prevention,” Healy said.
“This is just my opinion, but even if it wasn’t cheaper, what’s the cost of cancer? What’s the cost to manage cancer?”
Not only that, but what’s the cost of HPV?
When Healy began her study, the role of HPV in cervical cancer was very controversial. Some studies showed the association, others didn’t. Researchers soon learned that the difference was in the type of test used.
Now, the challenge is in controlling HPV. “HPV has a very sexually transmitted profile. It’s not as easy to contain as, say, chlamydia or HIV, where you can use barrier protection like condoms. It doesn’t work for HPV. It’s so much more easily spread. Where you have populations with earlier onset of sexual activity, you see higher prevalence in those populations,” she said.
Researchers are currently testing vaccines to combat HPV, but the virus has hundreds of different strains, 13 of which have been proven to be cancer-causing. Future research in Nunavut will look into which of those strains are most prevalent in the territory.
“We want to be sure that the vaccine has the strain that we have here,” Healy said.
But for now, Healy’s recommendations are three-fold. First, she wants the liquid cytology test to be used universally. But her job with the GN puts her in a tough spot.
“I’m kind of in this position where I’m kind of being an advocate and I’m also inside, although I don’t determine policy for screening,” she said.
Second, she wants liquid cytology to be used in conjunction with HPV DNA testing in women over 30, for whom the DNA testing has proven to be most accurate.
And for those women who receive positive test results with cytology alone, she says the HPV test should be administered before they are sent to a southern hospital for further testing.
“In general,” she said, “I’d like to see more and more women asking for the better pap test.”