HPV vaccination substantially reduces risk for invasive cervical cancer
Click Here to Manage Email Alerts
Quadrivalent HPV vaccination substantially reduced the risk for invasive cervical cancer among Swedish girls and women aged 10 to 30 years, according to results of a study published in The New England Journal of Medicine.
“The results are something we have long suspected based on the established effectiveness of quadrivalent HPV vaccine against HPV infection, genital warts and high-grade cervical lesions,” Jiayao Lei, PhD, researcher in the department of medical epidemiology and biostatistics at Karolinska Institutet in Sweden, told Healio. “Now we are able to show, on the population level, a substantially reduced incidence of invasive cervical cancer after HPV vaccination by comparing vaccinated with unvaccinated women using nationwide Swedish registry data.”
Previous studies have shown the effectiveness of the quadrivalent HPV vaccine, which covers HPV types 6, 11, 16 and 18, in preventing high-grade cervical lesions. There is a lack of data, however, on the relationship between vaccination and subsequent risk for invasive cervical cancer.
Lei and colleagues assessed this association using data from Swedish demographic and health registries of 1,672,983 girls and women aged 10 to 30 years. Researchers followed the study population from 2006 to 2017, during which nearly one-third of the girls and women (n = 527,871) received at least one dose of the quadrivalent HPV vaccine, most before age 17 years.
The investigators controlled the analyses for age at follow-up, calendar year, county of residence and parental characteristics, including education, household income, mother’s country of birth and maternal disease history.
Results showed 19 of those who received the vaccine and 538 of those who did not were diagnosed with cervical cancer, for a cumulative incidence of 47 cases per 100,000 persons among the vaccinated group and 94 cases per 100,000 persons among the unvaccinated group.
Comparison of the vaccinated and unvaccinated groups showed an incidence rate ratio (IRR) of 0.51 (95% CI, 0.32-0.82) after adjusting for age at follow-up. After adjusting for calendar year, residential and parental characteristics, researchers observed an IRR of 0.37 (95% CI, 0.21-0.57).
Stratification according to age at the start of vaccination showed fully adjusted IRRs for cervical cancer of 0.12 (95% CI, 0-0.34) among girls vaccinated before age 17 years, 0.47 (95% CI, 0.27-0.75) among women vaccinated between ages 17 and 30 years, 0.36 (95% CI, 0.18-0.61) among those vaccinated before age 20 years and 0.38 (95% CI, 0.12-0.72) among those vaccinated between ages 20 and 30 years.
“Girls vaccinated at a young age seem to be more protected, probably because they are less likely to have been exposed to HPV infection given that the vaccine has no therapeutic effect against a preexisting condition,” Pär Sparén, MD, professor in the department of medical epidemiology and biostatistics at Karolinska Institutet, said in the press release. “Our data strongly support continuing HPV vaccinations of children and adolescents through national vaccination programs.”
“Our data highlight the significance of HPV vaccination and strongly support the importance to scale-up the coverage of HPV vaccination, especially the coverage in children and adolescents, in order to reduce the burden of cervical cancer,” Lei added. “The protection of the vaccine is more pronounced when vaccinated at younger ages.”
For more information:
Jiayao Lei, PhD, can be reached at jiayao.lei@ki.se.
Collapse
Click Here to Manage Email Alerts