In a recent study published in BMJresearchers in England evaluated the effectiveness of the human papillomavirus (HPV) vaccination program in reducing the prevalence of cervical cancers and grade 3 cervical intraepithelial neoplasms (CIN3) in socioeconomic groups.
Study: Effect of the HPV vaccination program on the incidence of cervical cancer and grade 3 cervical intraepithelial neoplasia by socioeconomic deprivation in England: a population-based observational study. Image credit: Prostock-studio/Shutterstock.com
Record
HPV vaccination, introduced in 2008 in England, has significantly reduced the prevalence of cervical cancer and grade 3 cervical intraepithelial neoplasia (CIN3), particularly among women. The decline was highest in the groups with the highest vaccination uptake and the youngest age at vaccination.
The social class gradient for cervical cancer incidence in England is one of the steepest and there are concerns that HPV vaccination may help those most at risk.
The National Health Service (NHS) in England aims to eliminate health inequalities, and low uptake of HPV vaccination among vulnerable people may exacerbate health inequalities.
Uptake of cervical screening is low among younger women in poorer areas, resulting in lower detection rates of cervical cancers and CIN3 identified by screening at age 25 than in less socioeconomically deprived areas .
HPV vaccine coverage has been consistently high, but it is important to investigate whether immunization, including the indirect effects of high uptake, contributes to minimizing health disparities.
About the study
In the present population-level observational study, researchers examined whether HPV vaccines reduced or increased cervical disease disparities.
The researchers replicated findings from a cancer registry analysis to investigate whether the previously observed high efficacy of the HPV vaccine remained after an additional year of follow-up.
They used pooled data to assess the impact of the vaccination program on socioeconomic disadvantage. The study included women living in England aged 20 to 64 years who had been diagnosed with cervical cancer (n=29,968) or CIN3 (n=335,228) between January 2006 and June 2020.
The primary endpoints were the incidence of invasive cervical cancer and the incidence of CIN3. The researchers used the Index of Multidimensional Deprivation (IMD) to quantify socioeconomic deprivation in areas such as health, employment and income.
The index ranks the lowest overproduction areas from most to least socioeconomically deprived and divides them into five groups, with groups 1 and 5 representing the 20% poorest and 20% wealthiest areas, respectively.
The researchers used International Classification of Diseases, Tenth Revision (ICD-10) codes from the NHS England National Disease Registration Service (NDRS) database to identify cervical cancers and CIN3.
They obtained estimates of the female population for the average year from the UK Office for National Statistics (ONS) website. They used age-period-cohort Poisson regression modeling to investigate the incidence of CIN3 and cervical cancer.
Results
Among women routinely vaccinated at age 12 to 13 years, the age-adjusted standardized incidence rates for cervical and CIN3 cancers were 84% and 94% lower in an additional year of follow-up (July 1, 2019 to June 30, 2020 ) compared to the reference group of women who were not offered HPV vaccines. By mid-2020, HPV vaccines would have saved 687 predicted cervical malignancies and 23,192 CIN3.
The researchers found the highest rates of cervical cancer among women from the most deprived socio-economic areas (192 and 199 for the first and second quintiles, respectively) and the lowest among women in the least deprived quintile (61 cancers prevented), but the vaccination program had a significant impact on all levels of deprivation.
CIN3 incidence decreased more among women who received booster vaccinations in the least socioeconomically deprived areas than in the most. The number of women with CIN3 avoided was high across all deprivation categories and highest among women living in the poorest areas: 5,121 and 5,773 in the first and second quintiles, respectively, compared with 4,173 and 3,309 in the fourth and fifth quintiles .
The significant reduction in cervical cancer incidence from highly deprived to less deprived areas seen in the unvaccinated reference group was not evident among those who received the vaccination.
conclusion
Based on the study’s findings, the HPV vaccination program in England significantly reduced rates of cervical malignancy and neoplasia across socioeconomic levels, particularly among women who received regular vaccinations.
However, the highest rates remained among women in the poorest neighborhoods. The researchers found that the significant downward slope from high to low poverty seen in the unvaccinated reference sample was not present among those offered immunization.
The effectiveness of national HPV vaccination was maintained during the additional year of follow-up (between July 2019 and June 2020), confirming previous findings and encouraging the use of more limited cervical screening in cohorts with high vaccine coverage aged 12–13 years.
Journal Reference:
Milena Falcaro, Kate Soldan, Busani Ndlela, and Peter Sasieni, (2024) Impact of the HPV vaccination program on the incidence of cervical cancer and cervical intraepithelial neoplasia grade 3 by socioeconomic deprivation in England: a population-based observational study. BMJ 2024;385:e077341, doi:http://dx.doi.org/10.1136/bmj-2023-077341.
