Quadrivalent human papillomavirus (HPV) vaccination was associated with a substantially reduced risk of invasive cervical cancer, according to data published in The New England Journal of Medicine.
This study followed an open population of 1,672,983 Swedish girls and women between 10 and 30 years of age until they reached 31 years of age. Of these, 527,871 received at least 1 dose of HPV vaccine during the study period from 2006 through 2017 with 438,939 (83.2%) receiving the vaccine before the age of 17.
Cervical cancer was diagnosed in 19 women who had received the vaccine and 538 who did not receive the vaccine. The cumulative incidence in each of these groups was 47 and 94 cases per 100,000 persons, respectively, by 30 years of age. In both the vaccinated and unvaccinated groups, the cumulative incidence of cervical cancer increased rapidly at 23 years of age. For women who received the vaccine before 17 years of age, cumulative incidence was 4 cases per 100,000 persons by the age of 28 years, while for those receiving the vaccine at 17 years of age or later, cumulative incidence was 54 cases per 100,000 persons by the age of 30 years.
After adjustment for age at follow-up, the incidence rate ratio between vaccinated and unvaccinated groups was 0.51 (95% CI, 0.32-0.82). After adjusting for all covariates, the incidence rate ratio for women vaccinated before 17 years of age was 0.12 (95% CI, 0.00-0.34), and for women vaccinated between 17 and 30 years of age it was 0.47 (95% CI, 0.27-0.75).
Investigators note that a small proportion of vaccinated women were misclassified as unvaccinated in the study. Of greater concern is the possibility that the relationship of
HPV vaccination and the risk of cervical cancer is confounded by other factors. Potential lifestyle and health confounders could not be excluded. Relationships between the number of vaccine doses and cervical cancer risk could not be reliably estimated.
This “quadrivalent HPV vaccination was associated with substantially lower risk of invasive cervical cancer,” with a greater benefit to “women who were vaccinated at a younger age,” concluded study authors.
Disclosure: A study author declared affiliations between their employer and a vaccine manufacturer. Please see the original reference for a full list of author’s disclosures.
Lei J, Ploner A, Elfström KM, et al. HPV vaccination and the risk of invasive cervical cancer. N Engl J Med. 2020;383(14):1340-48.