Cervical cancer rates in Canada and U.S. are dropping. Experts think they know why
A significant drop in the number of Americans who recently contracted cervical cancer in the U.S. highlights the importance and effectiveness of the HPV vaccine — a success story that is also playing out in Canada, according to Canadian experts.
Data released last week by the American Cancer Society shows a 65-per cent drop in cervical cancer incidence in the U.S. between 2012 and 2019 among women in their early 20s.
This age group of women were the first cohort to receive the human papillomavirus (HPV) vaccine after it was approved in the U.S. in 2006 — a data point that “foreshadows steep reductions in the burden of human papillomavirus-associated cancers, the majority of which occur in women,” the study says.
While directly comparable Canadian data is not available, cancer incidence numbers do show that Canada has seen a similar decline in cervical cancer rates over the last three decades.
In Canada, cervical cancer incidence decreased from a rate of 11 cases per 100,000 persons in the 1990s to 8.2 cases in 2018, according to data from the Canadian Cancer registry, which does not include Quebec figures.
These declines reflect the success of efforts to screen and vaccinate against HPV and should be celebrated, says Dr. Diane Francoeur, CEO of the Society of Obstetricians and Gynecologists of Canada.
“We’re so happy to finally see the impact because we’ve been doing the promotion of (the vaccine) for so many years, and now it’s time to celebrate,” she said.
“For us, it’s really, really good news and we are hoping to share it with every woman because to have a vaccine that can decrease cancer — I mean, it’s major.”
In Canada, an estimated 1,450 Canadian women were diagnosed with cervical cancer in 2022 and an estimated 380 died from it, according to Canadian Cancer Society data.
Cervical cancer is nearly always caused by the human papillomavirus, a common sexually-transmitted infection that is preventable through immunization and treatable if caught early enough, the Cancer Society says.
If not detected early, it can become a particularly challenging disease to treat, Francoeur says, which is why she believes more awareness is needed about the risks of this preventable disease.
“Cancer of the cervix is a very aggressive cancer because usually it grows locally, so it can invade the bladder and the intestine as well, so when we have to do the surgery, it’s a surgery that is really aggressive,” Francoeur said.
Most provinces vaccinate children against HPV in late elementary or middle school and in 2020, Health Canada extended the age for men to receive the vaccine to between 27 and 45.
It had been previously been approved for use in boys and men nine to 26 and girls and women from nine to 45.
Overall, HPV vaccination coverage from school-based programs for 14- to 17-year-old females in all of Canada was estimated to be at about 87 per cent in 2019, according to the childhood National Immunization Coverage Survey.
But vaccination coverage in different parts of Canada varies widely.
Provincial data shows Atlantic Canadian provinces have some of the highest rates of HPV vaccination from school-based programs, with Newfoundland at the top with 91 per cent of its Grade 6 students vaccinated against HPV, according to the Canadian Partnership Against Cancer.
Prince Edward Island was not far behind with 84 per cent of its Grade 6 students having received the vaccine in 2018-19, according to provincial data.
In Saskatchewan, 81 per cent of its 17-year-old students received the vaccine in 2018, while New Brunswick and Nova Scotia were at 75 per cent and 73 per cent respectively for their Grade 7 students in the same year, according to provincial data.
Meanwhile, in Ontario and Manitoba, only 61 per cent of 17-year-old students received the vaccine in 2019 and 2020, respectively, which shows some provinces have work to do, Francoeur said.
Francoeur noted that getting school-based vaccination programs approved across Canada took significant effort, due to pushback from some parents who were uneasy with the virus’ association with sexual activity in younger teens.
Now, Francoeur says she worries a rise in anti-vaccine sentiment in the wake of the COVID-19 pandemic could erode the gains that have been made in seeing more uptake of the vaccine in schools.
“There’s a lot of anti-vax people who unfortunately claim that there could be side-effects of this vaccine — yet the only side effects that we’ve seen are good.”.
Francoeur, who is a pediatric gynecologist, noted that in the last three or four years, she has seen far fewer babies suffering the impact of women with genital warts — a side effect of some human papillomaviruses.
Babies born to mothers with these warts often had to undergo surgery under general anesthesia to remove warts in their throats and other parts of their bodies that had been transferred from the mother due to the virus, she said.
“It was a disaster, but we don’t see that anymore… we used to see them all the time,” Francoeur said.
“We mostly really rarely see women with genital warts, so this is another good impact of the HPV vaccination that people forget.”
Michelle Halligan, the director of prevention at the Canadian Partnership Against Cancer, says she, too, is pleased to see how HPV vaccination is leading to lower rates of cervical cancer in Canada and the U.S.
She says her organization is now focused on seeing Canada meet its committed goal to eliminate cervical cancer in the country by 2040.
Very few cancers have a vaccine that can prevent the disease, Halligan said, which is why achieving elimination will mean increasing HPV vaccine coverage.
“We’re going to need to really work to increase the awareness and the acceptability of the vaccine in our population, we’re going to need to boost uptake rates in school-based programs. They’re not where we want them to be,” Halligan said.
Improvements are also needed in the measurement and reporting of vaccine coverage in Canada to uncover who may be being missed by current immunization programs, particularly among more vulnerable populations, and how best to address vaccine hesitancy on a local level, she added.
“So, there’s a lot to be done, and I’m pleased to say we are funding public health partners across the country to really start to dig into this, uncover who is under-immunized, what are the barriers that they’re facing, and how do we come up with solutions to address those in the next few years.”
But even as challenges remain, Halligan says she’s excited to be working on the first ever initiative to eliminate a cancer in Canada.
“I think that people across Canada should be proud to live in a place that is actively looking at this. It’s a good story.”
by Global News
