HPV vaccination significantly lowers risk of cervical cancer

HPV (human papillomavirus) vaccination appears to significantly lower the risk of cervical cancer, researchers reported on Sept. 30, 2020 in the NEJM/New England Journal of Medicine.

“This is the first time that we, on a population level, are able to show that HPV vaccination is protective not only against cellular changes that can be precursors to cervical cancer but also against actual invasive cervical cancer,” said author Jiayao Lei, Ph.D, researcher at the Department of Medical Epidemiology and Biostatistics at Karolinska Institutet in Stockholm, Sweden. “It is something we have long suspected but that we are now able to show in a large national study linking HPV vaccination and development of cervical cancer at the individual level.”

“Girls vaccinated at a young age seem to be more protected, probably because they are less likely to have been exposed to HPV infection and given that HPV vaccination has no therapeutic effect against a pre-existing infection,” added co-author Pär Sparén, Ph.D., professor at the same department at the Karolinska Institutet.

The investigators utilized nationwide Swedish health registries to track 1,672,983 girls and women, ages 10 to 30 years, for 11 years (2006 through 2017). Among these subjects, more than 500,000 were vaccinated against HPV, most before age 17.

They evaluated the data for an association between HPV vaccination and the risk of developing invasive cervical cancer. They adjusted their 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.

They evaluated all data for a diagnosis of cervical cancer up to age 31.

The researchers identified a cervical cancer diagnosis in 19 women who had received the quadrivalent HPV vaccine and in 538 women who had not received the vaccine.

This translated to 47 cases per 100,000 among vaccinated women and 94 cases per 100,000 among unvaccinated women.

After adjustment, the analyses showed that HPV vaccination correlated to a significantly reduced risk of cervical cancer. Subjects vaccinated before age 17 achieved an 88 per cent reduction in their risk of cervical cancer compared to unvaccinated subjects.  Subjects who had been vaccinated between ages 17 and 30 halved their risk of developing cervical cancer, when compared to unvaccinated subjects.

“In conclusion, our study shows that HPV vaccination may significantly reduce the risk of cervical cancer, especially if completed at an early age,” Sparén said. “Our data strongly supports continuing HPV vaccinations of children and adolescents through national vaccination programs.”