While high-income countries like Canada could eliminate cervical cancer by 2048 through human papillomavirus (HPV) vaccination and screening, the gap with lower-income countries is widening. A study published in The Lancet by a team from Université Laval and the CHU de Québec – Université Laval Research Center shows that these inequalities could skyrocket within a few decades if nothing changes in terms of prevention.
"Currently, the incidence of cancer in lower-income countries is three times higher than in wealthier countries. If HPV vaccination coverage remains the same, it could be 12 times higher by the end of the century. Compared to Canada, we're even talking about 40 times higher," reports Marc Brisson, a professor in Université Laval's Faculty of Medicine and a researcher at the CHU de Québec-Université Laval Research Center, who led the study.
In 2020, the World Health Organization set three targets for eliminating cervical cancer, i.e. achieving an incidence rate of less than 4 cases per 100,000 women. The recommended strategy involved vaccinating 90% of girls before the age of 15, screening 70% of women, and treating 90% of precancerous lesions and cancers. Five years later, the research team wanted to determine whether countries were on track with this strategy.
"High-income countries like Canada are on the path to elimination, but that's not the case for many countries with the highest incidence rates, which have low vaccination coverage and limited screening," says Mélanie Drolet, an epidemiologist at the CHU de Québec-Université Laval Research Center. "The good news is that there are ways to catch up, but they will require significant investment from countries and international organizations."
Among these measures, Professor Brisson highlights the availability of new, lower-cost vaccines on the market and the option of administering just one dose instead of two. This would help reduce costs and allow for the introduction of additional programs such as vaccinating boys, which indirectly protects girls, or conducting catch-up campaigns, which involve vaccinating adolescents and young adults who did not receive the vaccine during preadolescence.
The research team modeled various scenarios to assess the impact of different prevention strategies, ranging from status quo—in which the widening of inequalities increases dramatically between low- and high-income countries—to the full achievement of WHO targets.
The researchers conclude that the best strategy for reducing inequalities between low- and high-income countries would be to combine the achievement of WHO targets with universal vaccination for girls and boys and the implementation of catch-up campaigns. "We could prevent nearly 37 million cases of cancer by the end of the century," says Professor Brisson. He acknowledges, however, that introducing large-scale screening can be difficult for many countries. In such cases, universal vaccination with catch-up campaigns would be a promising and accessible solution. It would enable the elimination of cervical cancer in the vast majority of countries without increasing screening, at a rate equivalent to the WHO targets.
For all possible scenarios, Professor Brisson stresses the urgency of taking action. "If we meet the WHO's targets in five years, we delay the benefits of vaccination," Marc Brisson points out. "In the meantime, hundreds of thousands of girls will be infected with HPV, develop cancer, and risk dying from it."
The study's authors are Marc Brisson, Mélanie Drolet, Guillaume Gingras, Jean-François Laprise, Éléonore Chamberland, Laia Bruni, Andrée-Anne Sabourin, Élodie Bénard, Cathy Ndiaye, and Ruanne V. Barnabas.
